In Norse mythology, what bridge does the giantess Móðguðr guard?

In Norse mythology, the giantess Móðguðr guards Gjallarbrú, the bridge crossing the Gjöll river.

Gjallarbrú appears in the story of Hermóðr’s journey to Hel. After Baldr dies, Hermóðr rides Odin’s eight-legged horse Sleipnir toward the realm of the dead. He reaches the bridge and meets Móðguðr, who identifies him and explains that Baldr has already crossed it.

The bridge is associated with the route into Hel rather than with the rainbow bridge Bifröst. Bifröst connects Asgard with the human world and is guarded by Heimdall. Gjallarbrú, by contrast, is part of the underworld journey and spans the river Gjöll.

The name is commonly translated as “Gjöll Bridge” or “Bridge over Gjöll.” Because both bridges belong to Norse cosmology, summaries sometimes conflate them, but the sources assign them different locations and functions.