The rainbow bridge between Midgard and Asgard; guarded by Heimdallr.
Bifrost, also called Bilröst in some manuscripts, is the burning rainbow bridge connecting Midgárðr to Ásgarðr. It was built by the gods with great skill and consists of three colors, of which red is the burning band that prevents giants and frost-beings from climbing it. Heimdallr guards the bridge at Himinbjörg, his hall at the bridge's heavenly end. He sleeps less than a bird and can hear grass growing and wool on sheep.
Grímnismál 29 mentions the bridge in the context of the gods riding over it daily to Urðarbrunnr. Thor himself may not tread upon it, as his passage would burn it up; he instead wades through the rivers surrounding the worlds. Völuspá 52 predicts that Bifrost will break when the sons of Múspell ride northward at Ragnarök. Fáfnismál 15 contains a brief reference in connection with fate-descriptions.
The bridge's name has been interpreted in various ways. 'Bi-' may derive from a word related to 'bivra' (to tremble, to shimmer) or alternatively be a prefix of unknown meaning. 'Röst' is related to 'rushing' or 'stream'. Another interpretation is that 'Bil' refers to the moment of vibration or shimmering, and the whole name can be read as 'the shimmering path' or 'the trembling bridge'. The rainbow's nature as an optical phenomenon gives the bridge its mythic character as a boundary object.
Sources in the Eddas
- Grímnismál 29
- Odin mentions that the gods ride over Bifrost daily to the assembly at Urðarbrunnr.
- Völuspá 52
- The völva predicts that Bifrost will break at Ragnarök when the sons of Múspell ride northward.
- Fáfnismál 15
- A brief reference to Bifrost in Fáfnismál's discussion of fate and the boundaries of death.
- Gylfaginning 13, 51
- Snorri describes Bifrost in detail, its colors, Heimdallr's guardian role, and its fate at Ragnarök.
Interpretive traditions
A What we know
Bifrost is a bridge connecting Midgárðr and Ásgarðr, consistently described as rainbow-like.
Heimdallr guards the bridge and is equipped with extraordinary sight and hearing.
The bridge breaks at Ragnarök under the advance of the sons of Múspell.
B What we think we know
Whether 'Bifrost' and 'Bilröst' are two names for the same bridge or reflect different traditions is linguistically debated.
Whether the bridge's burning nature is a fire mechanism preventing giants, or simply a description of the rainbow's appearance, is debated.
The relationship between Heimdallr and the bridge, whether his name is etymologically connected to the light of dawn, and whether this has cosmological significance, is debated.
C What we do not know
It is unknown how the bridge was originally built and what materials the three colors consist of in a mythological sense.
Whether Bifrost existed before the gods built Ásgarðr or was created alongside it is not specified.
What happens to the bridge's remnants after it breaks at Ragnarök is not described.