In Norse mythology’s Ragnarok, the rainbow bridge Bifröst is destroyed when the forces of Muspelheim cross it.
Bifröst connects the realm of the gods, Ásgarðr, with the human world, Midgard. It is guarded by Heimdall, who watches for approaching enemies and sounds Gjallarhorn when Ragnarok begins.
During the final events, the fire beings of Muspelheim cross the bridge, and Bifröst breaks beneath them. This destruction emphasizes the collapse of the boundary between the gods’ realm and the wider cosmos.
Bifröst is often identified with a rainbow, although the surviving texts also describe it as having fire and being strong. It should not be confused with Gjallarbrú, a bridge associated with the underworld journey, or Himinbjörg, Heimdall’s dwelling near Bifröst.