Bifrost

Bifrost is the bridge leading from the realm of the mortals Midgard to the realm of the gods Asgard, which the gods travel daily to hold their councils under the shade of the tree Yggdrasil. The bridge itself is the rainbow and its guardian is the god Heimdall. The red color was the flaming fire, which served as a defense against the giants. The bridge is destroyed at the end of the world, Ragnarök. It was built by the Aesir.