"In Norse mythology, Bifröst About this sound pronunciation (help·info) (Bifrost in Scandinavia) or sometimes Bilröst, is a burning rainbow bridge that reaches between Midgard (the world) and Asgard, the realm of the gods. The bridge is attested as Bilröst in the Poetic Edda; compiled in the 13th century from earlier traditional sources, and as Bifröst in the Prose Edda; written in the 13th century by Snorri Sturluson, and in the poetry of skalds. Both the Poetic Edda and the Prose Edda alternately refer to the bridge as Asbrú (Old Norse "Æsir's bridge").
According to the Prose Edda, the bridge ends in heaven at Himinbjörg, the residence of the god Heimdallr, who guards it from the jötnar. The bridge's destruction at Ragnarök by the forces of Muspell is foretold. Scholars have proposed that the bridge may have originally represented the Milky Way and have noted parallels between the bridge and another bridge in Norse mythology, Gjallarbrú. (wikipedia)