The Black Bridge is the opposite of the Bifrost, due to it leading to no realm at all, at least not in the same way that the Asgardians count the realms.[1] It is located at the edge of Asgard's territory, in the River Vimur, and it gives access to Utgard.[2]
History
The Black Bridge appeared over the River Vimur before a young Thor and Loki, who crossed it and reached Utgard.[2] Centuries later, Gaea opened the gate of Utgard and released the Utgard-Gods upon Midgard, coming into conflict with Thor.[3] The Black Bridge reappeared over the River Vimur, allowing the Executioner, Thanos and Thor to cross into Utgard.[1]