Deep below, beyond a dark river and a gold-roofed bridge, lies Helheim – the realm of the dead. Not the shining hall of the fallen warriors, but the place almost everyone else comes to: those who died of sickness and old age. Over them rules Hel, the daughter of Loki.
Helheim (or simply Hel, like the goddess herself) is the stillest of the nine worlds. No fire, no frost, no war – only the long rest. The way there leads niðr ok norðr, ‘downward and northward’.
The Edda paints the road to Helheim most vividly at the death of Baldr, the shining god: the messenger Hermod rides nine nights on Odin's horse Sleipnir through dark valleys until he comes to the river Gjöll. Over it leads the golden bridge Gjallarbrú, guarded by the giantess Modgud. Beyond lie the death-gate Nágrind and Hel's high hall Éljúðnir, where Baldr sits in the seat of honour – and yet may not return, because not every being weeps for him.
“Then Hermod rode on until he came to the Gjöll bridge, which is thatched with gleaming gold.”Prose Edda (Gylfaginning), Baldr's death; public-domain tradition
Valhalla & the Einherjar · What comes after Ragnarök? · Niflheim · The Nine Worlds · The Norse pantheon.
Snorri Sturluson, Gylfaginning (c. 1220). Völuspá, Baldrs draumar (Poetic Edda), English public domain: Henry Adams Bellows (1923). Scholarship: Rudolf Simek, Dictionary of Northern Mythology; Hilda R. E. Davidson, The Road to Hel.