Asgard was one of the 9 worlds, and the home of the warrior gods and goddesses of the Norse. Only the best and strongest warriors were admitted after death during battle, and was only accessible by crossing Bifrost (the rainbow bridge). The gods in Asgard were called the Aesir, and the goddesses were called Asynjur. Odin was the king and ruler, and his wife Frigg was the queen. Each main god had his own main mansion.
The walls of Asgard were built by Hrimthurs for protection from enemies including giants. He asked for Freya’s hand, the sun and the moon, as payment for his labor. Odin agreed, but under the condition that it be completed within six months time. With only a few days left, when Hrimthurs and his magic horse Svadilfari were almost finished, Loki turned himself into a mare and lured Svadilfari away, leaving Hrimthurs to finish the work himself. Unable to complete his work in time, their agreement was not fulfilled and no payment was made. (More 1, 2)
Found within Asgard is Valhalla, whose walls were made of wooden spear shafts, and roof was made from golden shields. This was the place where half of the vikings slain in battle await their final conflict (the other half were given to Freya, who chose the ones she wanted). Every morning, those in Valhalla prepared for battle, walked out into the plains of Asgard and fought. Every evening the warriors returned to be restored from their battle injuries and feast on roast pork and mead. Standing on the roof of Valhalla there was a goat named Heidrun. It ate from the branches of the tree of life, while mead flowed from its udder down to a huge tub for those in Valhalla to drink every evening.
In the middle of Asgard was the plain of Idavoll, in which to decide important issues, the Aesir would meet in the hall of Gladsheim and the Asynjur would meet in the hall of Vingolf. (More 1)
The tree of life (Yggdrasil), including Asgard, grew from the Well of Urd, as the Poetic Edda describes:
There stands an ash called Yggdrasil,
A mighty tree showered in white hail.
From there come the dews that fall in the valleys.
It stands evergreen above Urd’s Well.The gods would also meet at the Well of Urd every day, beneath the Asgard root. The purpose of this would be to review the past as it nourished the present.