Asgard

After the sons of Borr have shaped the earth and made the first humans, Askr and Embla, Snorri says they next built themselves a stronghold in the middle of the world, called Ásgarðr. The gods and their kin lived there, and from his high seat Hliðskjálf Odin could see over all worlds. When Gangleri asks what Odin did once Ásgarðr was built, the High One answers that he seated rulers to judge with him at Iðavöllr, in the middle of the stronghold. Their first work was a temple with twelve seats besides Odin's high seat, gold inside and out, called Glaðsheimr; the next was Vingólf, the sanctuary of the goddesses. Then they built a forge and worked so much gold that every dish and every harness was made of it. That was the golden age, and it lasted until women came out of Jötunheimar and spoiled it. Völuspá (st. 7–8) tells the same scene: the Æsir meet on Iðavöllr, build altar and temple, set up forges, play at tables in the meadow and lack no gold, until three giant maidens arrive.
The sources rarely say which halls stand inside Ásgarðr. Skáldskaparmál puts the golden-leaved grove Glasir 'in Ásgarðr before the doors of Valhalla', and Grímnismál 8 sets Valhalla in Glaðsheimr. Snorri sets other halls, such as Breiðablik, Himinbjörg and Odin's Valaskjálf, in heaven, and never reconciles the two pictures. The stronghold had gates, the ásgrindr, inside which the gods killed the giant Þjazi. In Gylfaginning 42, after the gods had settled Miðgarðr and built Valhalla, a builder offered them a fortification proof against the giants, in return for Freyja, the sun and the moon; Snorri calls it simply a borg and does not name Ásgarðr here. The gods gave him one winter and no helper but his stallion Svaðilfari. Three days before summer the work had almost reached the gateway. Loki, as a mare, lured the stallion away, the builder flew into a giant rage, and Thor broke his skull with Mjöllnir. Snorri quotes Völuspá 25–26 on broken oaths, though the poem never names the builder. Separately, Völuspá 24 says that in the first war, against the Vanir, 'the board-wall of the Æsir's stronghold was broken'.
Snorri also gives Ásgarðr a learned, human history. In the same chapter of Gylfaginning he adds 'we call it Troy', and his Prologue explains the Æsir as men of Asia. Ynglinga saga (ch. 2) makes Ásgarðr the chief city of Ásaland, east of the river Tanakvísl, which Snorri says flows into the Black Sea. Odin leaves his brothers Vé and Vili in charge of it (ch. 5) and moves north; after his death the Swedes believed he had gone to 'the old Ásgarðr' to live forever (ch. 10). The frame of Gylfaginning plays on both versions: King Gylfi travels to Ásgarðr, the Æsir meet him with illusions, and at the end the hall vanishes and he stands on a level plain.
The Eddic poems rarely use the name. Among the poems about the gods, only two have it: Hymiskviða 7, where Thor and Týr travel all day 'from Ásgarðr', and Þrymskviða 18, where Loki warns Thor that giants will soon live in Ásgarðr unless he wins back his hammer. Þrymskviða 5 and 9 speak of ása garðar, 'the Æsir's courts', and Völuspá 24 of borgar ása. A skaldic half-stanza by Þorbjörn dísarskáld, quoted in Skáldskaparmál, also says that Thor 'has defended Ásgarðr' with his strength. Ásgarðr does not outlast Ragnarök. Bifröst breaks under the sons of Múspell, and afterwards, Snorri says, Víðarr and Váli live on Iðavöllr, 'where Ásgarðr was before'. Thor's sons Móði and Magni bring Mjöllnir there, Baldr and Höðr return from Hel, and, as in Völuspá 60–61, the gods find in the grass the golden game-pieces they had owned in the old days.