Bifrost (or Bif-raust)
Bifrost (Or Bif-Raust)
in Norse mythology, is the bridge which joins heaven and earth, the rainbow. The Asas ride over it to their place of assembling by Urdar's well. Heimdall with his Gjalderhorn guards it, so that the Asas are not suddenly attacked. It is very skilfully built of air, water, and fire. The green is the water, blue is the air, and red is the fire. The first two elements would make it strong enough for the Asas; still fire has been added in order that the mountain-giants (Berg-riesen) cannot pass over.