Odin's high seat in Asgard from which he can survey all worlds.

Hlidskjalf is described in Grímnismál and Skírnismál as an elevated seat in the hall Valaskjálf. From it Odin can see across all nine worlds and everything that occurs within them.

In Skírnismál, Freyr sits on Hlidskjalf without permission and sees Gerðr in Jotunheim, setting the tale in motion. The seat symbolises the all-seeing knowledge that belongs to Odin.

Attestations

Grímnismál, Poetisk Edda (ca. 1270, Codex Regius)
Primary poetic attestation for Hlidskjalf.