urðarbrunnr (old norse for the "well of urðr") is a well in norse mythology. it is situated under the yggdrasil or the world tree. norse mythology is a version of the older northern germanic mythology. the gods would travel via the bifrost with the exception of thor as it was thought that he would break the bridge which took the form of a rainbow, to urðarbrunnr. here they would meet and decide things, presumably laws of nature and magic and love and war.