The place-name Iðavöllr only occurs in Völuspá 7 and 60 (created from the parallel verses in the Codex Regius mss. R58 and Hauksbók mss. H32). Snorri incorporates this place-name into his fictional narrative, in which the Aesir are historic human beings, in Gylfaginning 14 and 53, where he paraphrases and seeks to explain these verses in the context of his story. So any information we can gather about Iðavöllr is dependent on these passages. (We may also wish to consider the similar term Niðavöllr in Völuspá R36).

Gylfaginning 9: When the sons of Borr were walking along the sea-strand, they found two trees, and took up the trees and shaped men of them: ... Next they made for themselves in the middle of the world a city which is called Ásgard; men call it Troy. There dwelt the gods and their kindred. .... that kindred which we call the races of the Æsir, that have peopled the Elder Ásgard, and those kingdoms which pertain to it; and that is a divine race, [A. Broedur translation and hereafter].
 
Gylfaginning 14: "In the beginning he established rulers, and bade them ... give counsel concerning the planning of the town; that was in the place which is called Ida-field [Iðavöllr] in the midst of the town. It was their first work to make that court in which their twelve seats stand, and another, the high-seat which Allfather himself has. That house is the best-made of any on earth, and the greatest; without and within, it is all like one piece of gold; men call it Gladsheim.

The name Iðavöllr only occurs in Völuspá 7 (of which we have 2 variants, R7 and H7), and 60 (of which we have two variants, R58 and H32)  and we find a remarkably similar term in the same poem, Niðavöllr in R36.
 
Iðavöllr first appears during the creation story, immediately after the Sons of Borr had lifted up the shores from the sea, and created Midgard and set the sun, moon and stars on their courses (Völuspá 4,6), but notably before  the creation of the dwarves in verses 9-10, and man in verses 17-18. So, in the earliest days of creation, long before it was complete, the “Aesir”, gathered on Iðavöllr, where they forged tools and treasures, a task which would eventually fall on the as-yet-uncreated dwarves. The verses provide few clues as to where this place is:

From this we gather that the oldest gods, consisting mainly of Odin and his brothers working with their maternal uncle Mimir (Hávamál 140), initially met together on a plain and set up an altar and built forges, before man or the dwarves were created. It seems to be the sacred space established by the gods at the beginning of time, and may be the archetype upon which all worship is founded. Here they play tafl in a “tún” and are happy until three terribly-powerful thus girls come out of Jotunheim. By the language these cannot be the Norns as many assume, and most likely refer to Gullveig-Heid who is burnt and reborn three times, yet still lives; she is introduced immediately after the Norns in Völuspá R21-22. In Hyndluljóð 32, Heid is the daughter of the giant Hrimnir.  The terms þurs and ámáttki only apply to the most powerful, hostile beings. In Volsungasaga 2, we find Hrimnir’s daughter as a maid-servant of Frigg and “wish-maiden” of Odin. Völuspá 8 holds her responsible for ending the Golden Age [which has no bearing on the question of where Iðavöllr are located.]
 
The reappearance of Iðavöllr after Ragnarök best sheds light on where this place is located. Clearly, it is not “earth” (i.e. Midgard) risen anew. The poet informs us that the old Earth was burnt and sank into the sea. In the preceding verses the names of the Earth goddess are invoked in quick succession (R54) before she and her husband die. Ursula Dronke (1997) believed this repetition of Earth’s names was intentional. In her commentary on Völuspá 53/2 (R54), she observed: “The emphasis upon Þórr’s mother, the earth, is deliberate here, as men are leaving that heimstöð forever.” Frigg is ironically called Hlin, “the Protectress”, when Odin goes to meet the Wolf, and Freyr faces Surt (R52). Odin is sardonically called Sigföðr “Victory-Father”, literally in the jaws of defeat. His son Vidar shall avenge him.
 
Asgard too has been destroyed. Fire licks against heaven itself. Yggdrassil itself catches fire, although we know it will not perish. Fjölsvinsmál 20 says of Mimir’s Tree fellir-at hann eldur né járn, “neither fire nor iron can fell it.”

Midgard and Asgard have been completely destroyed. Heaven and Earth are burnt up and sink into the sea. Only the Tree remains. But then, out of the sea, something emerges:

1. the golden tafl pieces that the gods had owned in the early days (R59, H53)
2. a land without evil, where Baldur and Höður are found (R60, H54)
3.  Unsown fields that grow grain (R60, H54), which are “eternally green”
4. Hoenir, now restored to his role as a god (R61, H55)
5. Nidhögg flying neðan frá Niðafjöllum, “down from the Nida-fells” (R63, H58)

1. The golden tafl pieces that the gods had owned in the early days (R59, H53)
 
The golden tafl pieces that the gods had owned in the early days are found again in the grass (R59, H53). This statement should be compared to the phrase Teflðu í túni, teitir váru, “They played tafl in the tún” from Völuspá 7 above. The term tún refers to an enclosed grassy plot, with multiple buildings. It is the root of the English word ‘town’. The oldest gods built a hof and a hörg here, within this enclosure, and “tafled” in the grass yard. During the Golden Age they played tafl, a game in which a king and his men defend the center, while being attacked on all sides. The situation is that of an inngard, surrounded by an utgard, the very pattern of the Norse cosmos. In the beginning it’s just a game, but one which will become the real world situation of the gods, at the end of the Golden Age, when they will have to defend against attacks from all sides.
 
The gods had no want of gold until three dangerous thurs girls came out of Jötunheim. I would suggest this is a reference to Gullveig-Heid, the threefold witch in Völuspá R21-22, who spread seiðr and spá among mankind, becoming “ever the delight of evil people” (R22) or “evil women” (H27). This figure, daughter of the giant Hrimnir, appears to work at odds with Heimdall, who also travelled between homes, sanctifying culture, the classes, and teaching runes to the nobility (Rigsthula, cp. Völuspá’s opening “A hearing I pray all holy kind, Heimdall’s sons, high and low”).

Notably, Völuspá R36 places golden halls (salr ór gulli ) on Niðavöllr when speaking of Niflhel. In the preceding verses, Loki is bound under Hveralund (R34, a possible allusion to Hvergelmir, and its turbulent waters), a river filled with weapons (R35), and two subsequent verses describing the hall on the Nastronds and Nidhögg tearing the corpses of men (R37-38). This verse appears between them:

So somewhere near the frozen wastes of Nifhel and its shore, the Nastronds, where Nidhögg tears men’s corpses, we find the dwarf Sindri’s golden hall on Niði’s plains, and on “Not-Cold”, we find the giant Brimir’s beer-hall. Brimir can be identified as either Ymir or his son Mimir from the known references, although I think Mimir is the stronger candidate, primarily due to this verse.[1] Mimir is associated with the dwarves (see below), and drinks from his mead-well every day (R28). Suffice it to say that a giant named Brimir has a famous mead-hall in a frost-free region, somewhere near Niflhel. In Saxo Book 8, we find a similar situation, where the giant Geirrod (who resides in Niflhel after being killed by Thor) has a brother named Gudmund who rules a neighboring kingdom filled with riches and gardens. Geirrod and Gudmund’s lands are connected by a bridge. In the Fornaldarsagas, this giant named Gudmund of the Glæsirvellir (‘the glittering plains”) is a recurring character, and dwells in an abundant land.

[1] Compare Völuspá 9, Sigrdrifumál 14, and the additional line added to Grímnismál 44 in mss. AM 748 4to.

Gudmund and his children, when described, are richly dressed as in Helga þáttr Þórissonar  ch. 1. In Þorsteins þáttr bæjarmagns, chapters 5, Gudmund and his men wear regal attire:
 
“5. Now Thorsteinn saw three well-armed men riding, and so huge that he had never seen such large men before. The one who rode in the middle was the largest, in clothes woven through with gold, on a pale horse, and the two others rode on gray horses in red scarlet clothes. ...The biggest man took a gold ring from his finger and gave it to Thorsteinn. It was three aura in weight. Thorsteinn said: "What is your name, and from what background are you, and into what land have I come?"
 
"Gudmund is my name. I rule that place which is called Glaesir Plain. ...A great river divides our land," said Gudmund. "It is called Hemra. It is so deep and strong, that no horses can ford it, except those which we companions ride. Those others have to ride to the source of the river, and we meet in the evening."
 
Hervorar saga og Heiðriks, chapter 6, describe him in the manner of a heathen god:
 
“6.  "It is said that in days of yore there was a country up north in Finnmark called Jotunheim, and to the south, between there and Halogaland, lay Ymisland.  ...Gudmund was the name of a king in Jotunheim. His home was called Grund and his land Glasisvellir. He was a great worshiper of the old gods. He was a wise and powerful man and so old—and all his men too—that they each lived many times the normal span. And because of this, heathens believe that it must be in his realm that Óðains-akr [The Acre of the Not-Dead] is to be found, that place to which anyone who comes is so healed that sickness and old age vanish from them and they cannot die. It is said that after Gudmund’s death, folk worshipped him with sacrifices and called him their god.  One day he was playing tafl...."
 
Egils saga einhenda ok Ásmundar berserkjabana refers a giant with 18 daughters, who possesses three treasures, which one must go to the underworld [undirheima] to retrieve: a cloak that cannot burn, a horn that cannot be emptied, and a chess set that plays itself, (ok skylda ek fara í undirheima ok sækja þrjá kostgripi: skikkju þá, sem eigi mætti í eldi brenna, ok horn þat, er aldrigi yrði allt af drukkit, ok tafl þat, sem sjálft léki sér, þegar nokkurr léki annars vegar.).
 
Surely, Gudmund, widely remembered in the Fornaldarsögur, is a remnant from heathen times. So who might this noble giant, rich in treasure be?   According to the Saga, “heathens believe” that his realm is Óðains-akr [The Acre of the Not-Dead]. He expressly plays tafl in his lush underground kingdom, protected by mighty rivers.
 
 
2. A land without evil, where Baldur and Höður are found (R60, H54)
 
Grímnismál 12 informs us that Baldur’s home, Breidablik is the place “where fewest baleful runes are found”, er ek liggja veit fæsta feiknstafi. Snorri places Breidablik in heaven, where the human Aesir found Urd’s well after building a bridge to heaven (Gylfaginning 17). Grímnismál does not inform us where this hall is located. Before Ragnarök, Baldur and Hodr, of course, resided in Hel.
 
In Baldrs Draumar, Odin first rides down to Niflhel, then encounters a dog “coming out of Hel” toward him, eið hann niðr þaðan niflheljar til; mætti hann hvelpi, þeim er ór helju kom. The dog chases Odin at length, until foldvegr (‘field-ways’, paths through green fields) rumbled under Sleipnir’s hooves.  There he sees Heljar rann, “Hel’s hall” (Baldrs Draumar 3).  We find a similar distinction between Hel and Niflhel in Vafþrúðnismál 43, which states níu kom ek heima fyr Niflhel neðan; hinig deyja ór helju halir, “I came to nine homes, down below Niflhel, where men die from out of Hel.” Here, the passage from Hel to Niflhel is described as a death, akin to the one a person experiences when passing from Midgard to Hel.
 
From Baldrs Draumar, we gather that Odin rode down to Niflhel, then rode toward Hel. He encountered a dog at the border of the two realms. After crossing into Hel, the dog chased him for a time. In Hel, with its green fields (foldvegr), Odin finds the place that Baldur will reside.  Inside, the benches are strewn with costly things and rich mead (skírar veigar) poured out in goblets stands covered with shields, awaiting Baldur’s arrival (verses 6-7).  Clearly, this is not the hall of Loki’s daughter described in Gylfaginning 34, “whose dish is Hunger and Famine her knife; ... Disease, her bed; Gleaming Bale, her bed-hangings.” Instead, we find a richly decorated mead-hall in the underworld anxiously awaiting Baldur. Might this be Brimir’s beer-hall on the “Not-cold”? When Hermod arrives here, he must leap a great wall which only Sleipnir can leap (Gylfagininng 49). We find such a wall in another account of Hel, in Denmark a generation earlier.   
 
 
3.  Unsown fields that grow grain (R60, H54), which are “eternally green.”
 
In Saxo Book 1, we find this description of the land of death:  
 
“8.14. While Hadding was staying there as a guest, a remarkable portent occurred. As he was dining, a woman beside a brazier, bearing stalks of hemlock, was seen to raise her head from the ground and, extending the lap of her garment, seemed to be asking in what part of the world such fresh plants might have sprung up during the winter season. The king was eager to find out the answer and after she had muffled him in her cloak she vanished away with him beneath the earth; it was, I believe, by the design of the underworld gods that she took a living man to those parts which he must visit when he died. First they penetrated a smoky veil of darkness, then walked along a path worn away by long ages of travellers, and glimpsed persons in rich robes and nobles dressed in purple; passing these by, they eventually came upon a sunny region, which produced the vegetation the woman had brought away. Having advanced farther, they stumbled on a river of blue-black water, swirling in headlong descent and spinning in its swift eddies weapons of various kinds; they were able to cross it by a bridge. On the other side they saw two strongly matched armies encountering one another, whereupon Hadding asked the woman their identity. ‘They are men who met their death by the sword,’ she said, ‘and who present an everlasting display of their destruction; in the exhibition before you they are trying to equal the activity of their past lives.’ Moving on, they found barring their way a wall, difficult to approach and surmount; the woman tried to leap over it, but to no avail, for even her slender, wrinkled body was not an advantage; she thereupon wrung off the head of a cock which she happened to be carrying and threw it over the enclosing barrier; immediately the bird, resurrected, gave proof by a loud crow that it had truly recovered its breathing,” [Peter Fisher translation].
 
 Saxo describes these nether lands below ground as “those parts which he must visit when he died” [or “the regions whither he must go when he died”, O. Elton tr]. It is the land of the dead. Lush vegetation grows there, even while it is winter on earth. After piercing a veil of smoke, they advance “along a path worn away by long ages of travellers”, the road to Hel, travelled by generations before them. There they find a river filled with weapons, and a bridge, all features of the heathen underworld. Like Hermod travelling to Hel to find Baldur, Hadding sees whole armies of men there. And sees men “persons in rich robes and nobles dressed in purple”, like Gudmund and his men; and a remarkable wall, a decapitated cock’s head thrown over the wall returns, resurrecting the rooster. Could this be Óðains-akr?
 
In Book 8, the adventurer Thorkill and his crew arrive at this place by sea, sailing “across the Ocean which girds the earth, putting the sun and stars behind your back, journey beneath the realm of night, and pass finally into the regions which suffer perennial darkness without a glimmer of daylight.” When they finally reach their destination, they disembark in a land “abounding in trackless forests, incapable of producing crops and haunted by animals uncommon elsewhere. There are many rivers, whose courses are churned into the foam of roaring rapids by the reefs embedded in their channels,” (14.6)  First they encounter the noble giant Gudmund, “a man of extraordinary stature” who greeted them  by name, introducing himself as Geirröd’s brother, who invited them home to be his guests. (14.7) “While they were travelling along, they discerned a river spanned by a bridge of gold. When they wanted to cross it Gudmund called them back, telling them that the bed of this stream formed a natural boundary between the human and the supernatural worlds and no mortal was permitted to step beyond it.” Gudmund, “who conscientiously guarded from danger all who landed there” (14.7), extolled the delicious produce of his garden and tried hard to lure the king into it to sample his fruits (14.11) to no avail. Thorkill and his men moved on from there, and “beheld in the near distance a gloomy, decayed town, looking most of all like a misty cloud (cp. Nifl, cloud, mist). Stakes raised at intervals along the battlements displayed the severed heads of men. Before the gates they saw dogs of uncommon savagery keeping vigilant watch over the entrance,” (14.13).  “The gate entry stood open high above them, but by propping up their ladders to reach it they gained the lofty point of access. Within, black misshapen specters thronged the city, and you could hardly tell which was more frightful, the sight or sound of these gibbering phantoms.” (14.12) Here they encounter the giant Geirrod and his daughters, whom Thor previously killed (14.15), and Utgard-Loki (here Loki himself) chained (14.20).
 
The tales of Hadding and Thorkill illustrate two different approaches to the underworld. Thorkill and his men sail northward, past Bjarmaland, to the shores of a dismal place, where they find the spirits of giants slain by Thor, and a host of misshapen specters. Clearly, this is Niflhel. Nearby, in an adjoining kingdom they meet  Gudmund, who has a verdant garden in an otherwise barren land, “incapable of producing crops”. Hadding, on the other hand, arrives in the land of death in the way common to most, traveling the road to Hel. He is brought here while still alive. An eddic poem calls this place, the Hadding-land, perhaps in reference to this event. Speaking of a drink which wipes away painful memories, like the waters of the underworld river Lethe in Greek myth,  Guðrunarkvida II, 21 says:

The Hadding-land's "uncut (i.e. ‘unharvested’) ears of grain" belong to the flora seen by Hadding in the blooming meadows of the underworld. The expression refers to the fact that the Hadding-land not only has imperishable flowers and fruits (like those found the noble giant Gudmund’s kingdom), but also fields of grain which do not require harvesting. Compare this with what Völuspá says of the new earth: "unsown shall the fields yield the grain" (munu ósánir akrar vaxa). Of this verse, Ursula Dronke states: The suggestion that iða- implies the evergreenness of this völlr, growing every year unsown is not appropriate after Völuspá 4/7-8 or before 59/1-2."
 
In the Hadding-land we find a dragon on a drinking horn filled with drink made of three liquid substances, which may refer to the three world-wells that feed Yggdrassil, using the terms Urðar magni [‘Urd’s strength’, the actual reading in Codex Regius[2]], svalköldum sæ [‘cool-cold sea’] ok sónum dreyra [the blood of Son]; compare Hyndluljóð 38’s jarðar megni, svalköldum sæ ok sónardreyra, as the drink that Heimdall receives at birth, before completing his mission on Midgard as Rigr. These can be related to the waters of Urd’s well which heal the Tree [Urðar magni]; Hvergelmir, the mother of all waters [svalköldum sæ]; and the mead in Mimir’s well, [sonar dreyra, ‘sacrifical blood’?] which is also compared to blood in the term “Brimir’s blood” Brimis blóði (Völuspá 9), indicating that the dwarves were created from Ymir’s flesh (Bláins leggjum) and the creative fluid in Mimir’s well.

[2] The Codex Regius mss of this line reads “urðar magni”. For evidence of this see R.C. Die Edda, Vol. I, p. 223, or Kommentar zu den Lieder der Edda, Vol. VI, p. 694, or just take a look at the manuscript. Here Urðar is frequently emended to jarðar  on the basis of Hyndluljóð 38.

In this and other passages, particular Sigrdrifumál 13-14, where it is associated with the mysterious hausi Heiðdraupnis ok horni Hoddrofnis, “Heid-draupnir’s skull and Hodd-rofnir’s horn.” Jens Peter Schjødt (Initiation Between Two Worlds, p. 116) says that while we cannot be sure if stanza 13 refers to Mimir at all, that “a certain possibility appears when other elements of the Mimir-complex are considered.” The names Heið-draupnir and Hodd-rofnir, which do not appear elsewhere, mean “Clear-dripper” and “Treasure-opener”. Their attachment to a skull and a horn refer to two phenomena connected to Mimir.  Völuspá 27 places Heimdallar hljóð at Mimir’s well, and verse 45 mentions both Heimdall’s horn and Mimir’s head.
 
4. Hoenir, now restored to his role as a god (R61, H55).

Hoenir is Odin’s brother, who assisted in the creation of the world and mankind (cp. Gylfaginning 5-6 with Völuspá 17-18). Snorri tells us that Odin and his brothers, Vili and Ve, were walking along the seashore when they found two pieces of driftwood and created the first human beings from them. Völuspá 18, which Snorri does not quote but rephrases generically without names, attributes this event to Odin, Hoenir and Lodur. Thus Vili and Ve are Lodur and Hoenir.  Snorri’s probable source for the names Vili and Ve is Lokasenna 26, where the Sons of Borr are designated with the alliterative epithets Vidrir (Odin), Vili (Lodur) and Ve (Hoenir). In Ynglingasaga 4, Snorri directly associates Mimir and Hoenir, as hostages sent to the Vanir by the Aesir during the Van-As war. We are never told what became of him. So again we have a connection to Mimir.
 
According to Völuspá R61/H55, Hoenir reappears after Ragnarök, along with Baldur and Höður, “the two brothers” (brœðra tveggja). Snorri does not paraphrase or cite this verse at all in his Edda, although it appears in both manuscripts of Völuspá, and he mentions Hoenir as a hostage of the Vanir in Gylfaginning 23. The verse is obscure, but seems to indicate that after Ragnarök, Hoenir will be restored as a god, choosing lots as gods do, while dwelling with the children of the “two brothers” in Vindheim, the home of winds.  In this context, we should consider that the upper worlds, Asgard and Midgard, have been burned away, leaving the lower world with an open sky, the home of winds. Nor are Baldur and Höður the only pair of brothers in the new world. Vafþrúðnismál informs us that Odin’s sons, Vidar and Vali, as well as Thor’s sons, Magni and Modi will survive Ragnarök. Notably, Vali had once killed Höður as a revenge for Baldur’s death. In the new world, peace reigns.
 
Snorri's statement that Vidar and Vali, after Surt's fire has slaked, "shall dwell at Iðavöll, where Ásgard was before (Gylfaginning 53), is based on Vafþrúðnismál 50-51, where Odin asks:

The text does not say that Vidar and Vali will inhabit Asgard or the Idavoll, it says that they will inhabit vé goða, “the sanctuary of the gods”. Snorri equates this place with earth (jörð) rising from the Ocean in Völuspá R57, after Ragnarök. He previously placed Asgard on earth in Gylfaginning 9. I would compare this to the term hodd goða, "the treasure of the gods" in Grímnismál 28 and græna heima goða, “green home of the gods” in Hákonar Saga Aþalsteinsfóstra, ch. 28, which Snorri attempts to render as the "abode of the gods" in Gylfaginning 29.
 
Could this  vé goða be where the gods built hǫrg, hof, and afl in the early days (Völuspá 7), which now rises from the sea again "evergreen", complete with the golden tafl pieces they played with before the end of the Golden Age (Völuspá  7,8). Gudmund too is known to play tafl, perhaps the same magic tafl set that plays of itself if challenged, kept in the underworld with a horn and a magnificent robe, like the one Gudmund and his sons wear. Since Surt's fire has scorched the earth, and rose up to heaven itself, causing the stars to vanish, and setting Yggdrassil alight (Völuspá R55), where is this vé goða that Vidar and Vali will inhabit? And where did all that life come from without a new act of creation?
 
Evidence from multiple sources, a shown above, converges on this being a secluded kingdom in the lower world ruled by Mimir, the collector of treasures, known to many tribes.
 
 
5. Nidhögg flying neðan frá Niðafjöllum, “down from the Nida-fells” (R63, H58)
 
Most revealing, in the new “earth” we find a familiar creature, the dragon Nidhögg whose proper place is Niflhel in the north (Völuspá R63, H58).  He is one of the many serpents that gnaw on Yggdrasil’s roots (Grímnismál 34,35). In Völuspá, Nidhögg was previously mentioned along with the on the Nastronds, built of poisonous serpents in Völuspá R37-38, H34-35. Snorri places these same serpents in Hvergelmir which he locates in Niflheim (Gylfaginning 4, 15). Thus, this must be the northern root of the Tree. Hrafnagaldur Óðins 25 appears to confirm that: 

Mimir and Urd, who are older and more powerful than the gods, must be the boy and girl born together under Ymir’s arm. They seem to represent a more noble class of jotuns than those produced by his feet.  After Ragnarök, we also find Lif and Lifthrasir who emerge from Hoddmimis holt, “Hoard Mimir’s grove” in Vafþrúðnismál 45. The name Hoddmimir describes Mimir as the hoarder of treasures, a natural position for the master of the dwarves. Völuspá 10 calls Mótsognir, the master of all the dwarves, Þar var Mótsognir mæztr um orðinn dverga allra. It does not say he is the first dwarf created. That is Snorri’s understanding (Gylfaginning 14). After the gathered gods decide who shall create the dwarves from ór Brimis blóði ok ór Bláins leggjum, [Brimir’s blood and the Blue One’s limbs], Mótsognir is declared “the master of all the dwarves.” The name Mótsognir (Power-sucker) is most appropriate for Mimir, who is said to drink from his own well every day (R28). After a single draught of this mead, Odin first began “to bloom and grow wise”, giving him the fortitude and wisdom to create and rule the upper worlds. In the German medieval poem, "Biterolf," its hero possessed a sword made by Mimir the Old, Mime der alte, who was the most excellent smith in the world; and in Saxo Book 3, the hero Hotherus obtains a sword of victory and a wealth-producing arm-ring (like Draupnir) from Mimingus, (son of Mimir), a satyr in a remote cave in the far north.  Mimir’s relationship to the dwarves as master likely explains Völuspá R36’s reference to Sindri’s golden hall, and the giant Brimir’s beer-hall on Okolnir, the Not-Cold. Adjacent to Niflhel, we find Mimir’s domain, a “not-cold’ region where fruits and flowers grow, eternally green. If Mimir were identical to the giant Gudmund of Glaesirvellir, a recurring character in several Fornaldarsögur, then “heathens believe that it must be in his realm that Óðains-akr [The Acre of the Not-Dead]” can be found, (Hervorar saga og Heiðriks, chapter 6).
 
Snorri, although he misidentifies Mimir as a hrim-thurs (based on his interpretation of Grímnismál 31, see below), accurately reports that Mimir’s well lies “where Ginnungagap once was”, þar sem forðum var Ginnungagap, (Gylfaginning 15), the place where Ymir and Audhumbla first formed, and the place from which Lif and Lifthrasir will emerge after Ragnarök from Hoard-Mimir’s Grove, hoddmimisholt (Vafþrúðnismál 45).  Ginnungagap is the birthplace of all life.
 
From this we can conclude that Mimir’s realm lies in between the original world of ice to the north and the original world of fire to the south. It is a temperate region, perfect for the creation, sustenance, and preservation of life. The name Hodd-mimir applied to a place rich in treasures, draws our attention to an obscure phrase in Grímnismál 27. After giving a list of rivers that flow from Hvergelmir in Grímnismál 26 and 27, the poet says: þær hverfa um hodd goða, “these wind around the Hoard of the Gods.”  In Gylfaginning 29, after naming the same list of rivers found in these verses, Snorri states Þessar falla um ása byggðir,”these fall around the Aesir’s abode” indicating that he interpreted the phrase “hodd goða” as the home of the gods. But the word hodd means “hoard, treasure”, not abode, as in Helgakviða Hundingsbana I. 9: hodd Hniflunga ['Niflings' Hoard'].
 
Both the Cleasby-Vigfusson Icelandic-English Dictionary and Sveinbjörn Egilsson's Lexicon Poeticum incorporate Snorri’s paraphrase into their definitions of the word hodd, giving it a special meaning only applicable to Grímnismál 27. There and only there, Egilsson says that the word hodd “probably means ‘residence, homeland’” (antaga at betyde ‘bolig, hjemland’). Cleasby-Vigfusson adds “of this sense, which occurs in Heliand (Schmeller), the Grímnismál 27 is the single instance left on record.” So, clearly this special definition is yet another scholarly attempt to reconcile Snorri’s interpretation of an Eddic poetic passage with other known usages. Regardless of the obvious conflict, Snorri's translation is taken as accurate above the actual meaning of the word in every other Icelandic context. In fact, Snorri’s understanding has become the primary source for the interpretation of the term hodd goða. A supposedly similar usage in the Heliand, a Saxon source, is offered to support this assumption by Vigfusson. But does it really?  In the Heliand, the Old Saxon word horð, corresponding to the Old Icelandic hodd, is not in fact used of the city of Jerusalem as Cleasby/Vigfusson (via Schmeller) indicates, but instead used  only of the holiest of holies in the Jerusalem temple, where God manifested once a year.  In part, Heliand, Fitt 67, says:

5666 an themo uuîhe innan | uuundron gistriunid
5667 hêl hangoda | -- ni muostun heliðo barn,
5668 thia liudi scauuon, | huat under themo lacane uuas
5669 hêlages behangan: | thuo mohtun an that horð sehan
 

"The colorful curtain so wonderfully woven,
which for many a day had been hanging whole inside the shrine,
was torn in two down the middle—
people could then see the treasure hoard.”

When Christ dies, the veil of the temple spontaneously tears, and the holy chamber is exposed. Hebrews 10:20 clearly shows the curtain is symbolic of Christ’s body.  In Mark 15:38, the curtain was torn in two from top to bottom, opening up access to God.  Jesus is "the way, the light, and the truth," according to John 14:6, "no man cometh unto the Father, but by" him. G. Ronald Murphy explains that “the veil of the temple concealed the holy of the holies, the room which once contained the ark of the covenant. The Heliand interprets this concealed sacred possession of the Jewish people as a hidden Germanic treasure in the tradition of the last scenes of Beowulf, and the treasure of the Nibelungs hidden in the Rhine.”  So horð in the sense of a city or sanctuary does not actually occur in the Heiliand as Cleasby/Vigfusson state. Thus it is unlikely that the expression "hodd goða" means "the place where the Aesir live" as Snorri indicates. In the Heliand, the word horð only designates the most precious things which are concealed within a well-fortified inner sanctum, not the city as a whole.  Thus, in Grímnismál 27, the word hodd, which is the Norse equivalent of the Saxon horð, must mean something held sacred or valuable by the gods themselves, the well-fortified "hoard of the gods", ringed by several rivers in Hel. What could this be?
 
Because Snorri offers no explanation for it, the term Hoddmimis holt, is commonly interpreted to mean the World-Tree, based on a similar expression in Fjölsvinnsmál 20, which calls Yggdrassil, Mimameiðr, "Mimir's Tree." Mimir is well-known to own a well that feeds Yggdrasil; since he lives beneath it, the Tree can be called his. Metaphorically speaking, Lif and Lifthrasir, are precious treasures, gathered together and hidden underground like a seed which lies dormant through the winter waiting for spring. When the great fimbul-winter has passed, Lif and Lifthriasir will emerge from their hiding place and become the parents of a new race of men, without the need for a second act of creation. This metaphor is not unique in Germanic poetry. The Anglo-Saxon poem Exodus (l. 368) speaks of the contents of Noah’s ark in a similar fashion:

The Anglo-Saxon poetic version of Exodus 12:29-15:27 is found in the Junius Manuscript, one of the four manuscripts containing most of what remains of Anglo-Saxon poetry. Critics find it to be one of the most powerful of the Anglo-Saxon epic poems, comparable to Beowulf in its artistry and narrative strength.  Anglo-Saxon renderings of biblical stories tend to recast them in terms of Germanic culture. Exodus is no exception. In Anglo-Saxon imagery, meter, and wording it retells the history of the Israelites, reshaping the biblical story into an Anglo-Saxon image. The wording reflects Germanic culture. Here as in Vafþrúðnismál 45, the parents of a new world are referred to as a treasure-hoard. The human beings Lif and Lifthrasir reside in Hoard-Mimir’s grove, until the flames of Ragnarök have subsided and a new world has risen from the sea. Thus the expression hodd goða "hoard of the gods" appears to be a reference to the biological treasures hidden in Hoddmimis holt, Hoard-Mimir's grove, beneath the central root of Yggdrasill.  The meaning "realm of the gods" is based solely on Gylfaginning 38's paraphrase of the verse. So, when Grímnismál 27 says that these rivers “wind around the hoard of the gods” (þær hverfa um hodd goða), it does not mean the celestial home of the gods in Asgard, quite the opposite. In all probability, it refers to subterranean rivers surrounding a well-concealed hoard.  Rivers winding round it may act as a kind of moat, keeping unwanted visitors away. Forbidding rivers are a well-known feature of the underworld. The name Hvergelmir means “roaring kettle” and refers to water in turbulent motion. We are told that a multitude of rivers flow out of it (Grímnismál 26-29), including those that flow in Hel and those that Thor must wade through daily to arrive at Urd’s well. The other gods ride their horses from Asgard, over Bifrost each day, to arrive at Urd’s well. Thor, however, must walk or else his flaming chariot would cause the holy waters to boil. (Grímnismál 29).
 
Near the end of the list of rivers in Grímnismál 26-29, these are said to “flow down to Hel” er falla til Heljar héðan (Grímnismál 28), including Kormt and Ormt and the twin Kerlaugur, which Thor must wade through to on his way to Urd’s well. So the picture seems to be that Hvergelmir rests atop a mountain, likely designated as Niðafjöll in Völuspá R63, H58. Nidhögg dwells there gnawing on the northern root of the tree and náir (dead-men). A multitude of rivers flow down from the mountain, winding around and forming a moat ringing Mimir’s kingdom, which is an oasis of life in the kingdom of death. Here, living things are preserved in the archetypical sacred grove at the bottom center of the nine worlds, “where Ginnungagap once was”.  Yggdrassil, “Mimir’s Tree”, grows from the chasm, supporting the upper worlds. Flowing down from Niðafjöll, these rivers then er falla til Heljar heðan, “fall down into Hel” where Thor must wade through at least four of them to arrive at Urd’s well to “sit in judgement” every day. The remainder of the Aesir ride there on horses daily, over Bifrost, from their homes in Asgard (Grímnismál 30) which is located “up in Godheim” (Sonnatorek 2). So Grímnismál 30, in the context of the surrounding verses, indicates that the gods ride over Bifrost from their homes in heaven, downward to Urd’s well, located in the southern regions of the lower world, known as Hel, and not “up” from earth to heaven as Snorri says (Gylfaginning 15: upp um Bifröst).  And we can be sure that Bifrost connects Asgard with Urd’s well in Hel, and does not touch the earth, because in the skaldic poem Eiríksmál, when a great host of warriors arrive in Valhall over Bifrost, Bragi exclaims: "All the wainscoted walls are breaking as if Baldr might be coming again into Odin's hall!" [Lee Hollander’s poetic translation of Braka öll bekkþili/ sem myni Baldr koma / eptir í Óðins sali.] Baldur, of course, resides in Hel demonstrating that Bifrost connects heaven and Hel, not heaven and earth.

 While Hvergelmir is closely associated with the northern wastes of Niflheim, identical with Niflhel in later times, Urd’s well is closely associated with the south. Grímnismál 29 informs us that Thor cannot ride his flaming thunder-chariot here, which causes the ground to quake and rocks to crack (as in Haustlöng 16), lest the “holy waters boil”. Instead he must walk, wading through four rivers in Hel. Fafnismál 14-15 informs us what would happen if Thor decided to drive over the span. When Ragnarök is underway, Surt and his men storm the bridge. Völuspá R51 tells us that Surt arrives “from the south”, the southern realm of fire, opposite of Niflheim. From Grímnismál 29, 30 we know that one of the bridgeheads of Bifrost is near Urd’s well. So, this must be the bridgehead that Surt and his men storm. Now we understand why the mighty Thor cannot drive his flaming chariot over the bridge, it will break under the weight of fiery riders:

Thus, Urd’s well and the bridgehead of Bifrost found there are located nearest the southern world of fire. From Fafnismál, we gather that Surt lives south of Urd’s well, and rides northward to arrive there. Thus, her well is warm, and counteracts the serpents swarming in Hvergelmir, gnawing at the northern root of the Tree.  In contrast, swans swim in Urd’s well, according to Snorri.  In Völundarkviða 1, the swan-maidens, who accompany the elf-prince Volund to the Wolfdales, are poetically compared to the Norns themselves, and characterized as “southern maidens”:

The fact that these swan-maidens are three in number, spin near a sea, and fulfil örlög, associates them conceptually with the Norns, as described in Völuspá 19-20 and in Helgakviða Hundingsbana I, 1-4. They are associated with Urd’s well and the swans which swim in it, confirming that Urd’s well is located in the southern part of the lower world.  According to Grímnismál 29-30, the gods travel from their homes to hold court here daily (Grímnismál 29-30).  If it is located in the warm, southern portion of Hel, we come to understand what the purpose of this court is.  Fafnismál 10 informs us that “all men come to Hel” eventually, including warriors whose ultimate destiny is Valhall (Gisli Surrson’s Saga, ch. 24, which states that Hel-shoes are bound on the dead including those going to Valhall). Solarljóð 51 says that dead men “sit on the Norns’ seats 9 days”. Sigrdrifumál 10 informs us that mal-runes are most useful “in that court where men go into full judgement”. Thus in Hávamál 110, manna mál, the speech of men, is heard at Urd’s well. Hávamál 77 speaks of an eternal judgement on “each one dead”. All things considered, the thingstead by Urd’s well must be the Nordic court of the dead known to most all Indo-European religions.  Incredibly, the late 10th century skald Eilífr Guðrúnarson informs us that even “Christ sits in the south by Urd’s well” (Skáldskaparmál 52). From this we can conclude that Urd’s well was located in the warm, southern regions of the lower world, either near or above the original world of fire, from whence Surt hails (Surts sökkdalir). The green paradise of the heathens was not in the heavens at all, it was in Hel.
 
In his poem Hákonarmál, Eyvind Skaldaspillir makes Odin send the valkyries Göndul and Skögul "to choose among the kings of Yngvi's race some who are to come to Odin and abide in Valhall." The two valkyries proceed to Midgard, but when they arrive there they find that a battle between the Yngvi descendants, Hakon the Good, and the sons of Erik is imminent. Although he prevails, Hakon is hit by an arrow, and after the end of the battle he sits on the battlefield mortally wounded, surrounded by his men. The Valkyries, Göndul and Skögul, "maidens on horseback, with helmets on their heads, and with shields before them," are close to the king, who hears them converse.  Göndul, "leaning on her spear," says to Skögul that the wound will be the king's death. Skögul confirms this with the following words:

With these “green realms”, Eyvind does not mean a ride through the sky to Asgard. He otherwise distinguishes between blue and green in the poem, calling the sea blue (blámær, Heimskringla, Hákonar Saga Aþalsteinsfóstra, ch. 28).  What he expressly states, is that, according to his cosmological conception and that of his fellow-heathens, there were “green realms” inhabited by divinities on the route the valkyries took when they proceeded from a battlefield in Midgard back to Valhall and Asgard. But, since valkyries and the elect ride on Bifrost up to Valhal, Bifrost must be the connecting link between the realms decked with green and Asgard. The græna heimar through which the valkyries pass are therefore the green realms of the lower world. Hadding saw warriors on the road to Hel, and when Hermod first arrives in Hel, Modgud the guardian at the golden bridge, says that five fylki (companies) of warriors passed before him making less noise. These five fylki presumably died in battle together and were on the way to Urd’s well, where they will ride over Bifrost to Valhalla, as in Hakonarmál and Erikirsmál. In Njáls Saga, ch. 88, of the heathen Hrapp, who had burnt a heathen temple and stripped the idols of their riches, Hakon says: "The gods are in no haste to seek vengeance, the man who did this shall be driven out of Valhalla forever." (Magnusson and Pálsson tr). This suggests that gods are in no hurry to seek vengeance because there will be a time for certain redress in the future. Might this refer to the court at Urd’s well, to which the gods ride their horses “every day to sit in judgement”, (Grímnismál 29)? Might Urd’s well be located in Hel, to which “all men come” (Fafnismál 10)?
 
The only definite information we have about the placement of the roots of Yggdrassil, and their corresponding world-wells that feed them, comes from Grímnismál 31, which says:

To Snorri , based on the internal logic of his Prose Edda which consistently portrays the Aesir as human men, this meant:

1. One root in Hel (i.e. Hel-Niflhel, used interchangeably, the underworld realm of Loki’s daughter),
2. A second root with frost-giants (Mimir’s well, as stated in Gylfaginning 15: En undir þeiri rót, er til hrímþursa horfir, þar er Mímisbrunnr, “But under that root which turns toward the Frost-Giants is Mímir's Well,” he adds that it is located “where Ginnungagap once was”.
3. A third root with human men, i,e, the root by Urd’s well, up in heaven, over Bifrost, where the human Aesir gather each day to hold court.
 
[That should give us cause for a pause. Would a heathen skald ever refer to the Aesir as “mennskir menn”? Consider Sigrdrífumál 18 which makes a clear distinction between Æsir, Alfar, Vanir and mennskir menn, the same phrase found in Grímnismál 31.]
 

 To modern scholars, who generally adhere to Snorri’s text, but do not accept his statement that Asgard is an earthly city in Asia and arbitrarily place it back in heaven, this means:

1. One root in Hel-Niflhel, used interchangeably as Snorri does.
2. A second root with Mimir, a frost-giant according to Snorri.
3. A third root in Midgard, the home of human men, because it’s the most obvious reading.

This interpretation has the disadvantage of placing two roots and wells on the earthplane, one in Jotunheim and one in Midgard. It omits Urd’s well and root altogether; therefore, some scholars like Carolyne Larrington have proposed a fourth root, or Paul Bauschatz who reduced them to a single root and well.
 
To the ancient heathen skalds who composed Grimnismál 31, however, it most likely meant:

1. One root with Hel, who is Urd, the actual goddess of death who determines the birth, lifespan and passing of every man, including those who fall in battle. As evidence of that the youngest Norn, Skuld, is the foremost Valkyrie (cp. Völuspá R20 and R30). Loki’s daughter then is a side-figure and messenger of Urd, a harbinger of straw-death and disease, whose proper home is Niflhel, according to the description in Gylfaginning 34. Thus, her name cannot be “Hel.” Urd is the personal Hel and Hel is her kingdom. It is the heathen paradise. She is Mimir’s sister, the girl born under Ymir’s arm, along with her brother.
 
2. A second root with the Hrimthursar, the frost-giants of Niflhel, where the well Hvergelmir is located, swarming with serpents such as Nidhögg, and bound monsters like Fenrir and his father. Loki will lead them in the ship Naglfar at Ragnarök.
 
3. A third root with mennskir men, “living men, mortal men” can only refer to Mimir’s grove, from which Lif and Lifthrasir emerge after Ragnarök, along with Baldur, Höður and Hoenir.
 

This final interpretation results in an even distribution of three wells in a pattern corresponding to the world before creation, consisting of a world of ice to the north, a world of fire to the south and a great chasm (Ginnungagap) in between. One of each root of Yggdrassil corresponds to each of those three places. Life first rose when the molten flows from the south met ice-floes from the north to form Ymir and Audhumla. In time, Ymir’s corpse was thrown in the chasm to create Midgard and Asgard on the foundation of the original world. His flesh and bones became the world, his skull the canopy of the sky, and his blood became the sea, held in place by luðr, a giant millbox, supporting the millstones grinding at the bottom of the sea. Thus, at Ragnarök, when Surt’s fire destroys heaven and earth, and flames destroy the great-world mill upon which the ancient giants were ground into soil and rock to form the upper worlds (Vafþrúðnismál 35, var lúðr of lagiðr to be ground up, cp. Lokasenna 44-46), the sea busts free exposing Jörmungrund, “the great foundation” to the open skies (Vindheim). There we find the dragon Nidhögg in the north (corresponding to Niflhel); the bright hall Gimlé in the south filled with righteous men (corresponding to Urd’s hall); and Hodd-Mimir’s Holt, “Hoard Mimir’s grove” in the center. It is the sacred grove upon which all other sacred groves are fashioned, the holy place of the gods themselves where they first built hörg and hof. It is the place from which life first emerged and the same place from which all life will emerge after Ragnarök, once Surt’s fire has burned away heaven and Midgard, leaving only the original world that pre-existed creation. The new “earth” that rises from the sea, is actually the former lower world (Hel and Niflhel) which remains when the sea of Ymir’s blood dissipates. This is Iðavöll, the heathen holy place, the “hoard of the gods”.

The picture of the Heathen underworld which thus emerges, takes on the following appearance:

 
26. Eikþyrnir heitir hjörtr, (Eikthynir is the hart)
er stendr höllu á (that stands on the hall)
ok bítr af Læraðs limum; (and bites from Laerad's limbs)
en af hans hornum (and from his horns)
drýpr í Hvergelmi,(drips into Hvergelmir)
þaðan eigu vötn öll vega.(and thence all waters make their way)
 
27. Síð ok Víð, (names of rivers....)
Sækin ok Eikin,
Svöl ok Gunnþró,
Fjörm ok Fimbulþul,
Rín ok Rennandi,
Gipul ok Göpul,
Gömul ok Geirvimul,
þær hverfa um hodd goða, (they wind round the hoard of the gods)
Þyn ok Vín,
Þöll ok Höll,
Gráð ok Gunnþorin.
 
28. Vína heitir ein, (names of rivers....)
önnur Vegsvinn,
þriðja Þjóðnuma,
Nyt ok Nöt,
Nönn ok Hrönn,
Slíð ok Hríð,
Sylgr ok Ylgr,
Víð ok Ván,
Vönd ok Strönd,
Gjöll ok Leiftr,
þær falla gumnum nær, (fall close to men,)
er falla til Heljar heðan. (then fall down to Hel)
 
29. Körmt ok Örmt
ok Kerlaugar tvær,
þær skal Þórr vaða (these Thor shall wade)
dag hvern, (every day)
er hann dæma ferr (when he travels to judge)
at aski Yggdrasils, (at Yggdrassil's Ash, near Urd's well according to the next two verses)
 
.