Amon Ethir (S. Amon "hill" + ethir "spy") was raised artificially by the people of Finrod in the wide plain of Talath Dirnen, a league (approximately 5 kilometres[source?]) east of the Doors of Nargothrond above the river Narog. Over the years, trees grew on its flanks, but from its clear summit the watchers of Nargothrond could watch the lands about with the clear sight of the Elves, and so the hill got its name, Amon Ethir.
After the Sack of Nargothrond, the hill still stood, and it was here that Nienor encountered Glaurung the Dragon. Having plunged the land into a thick fog of dragon-reek, so that only the hill remained above the mists, he cast Nienor into a deep spell of forgetfulness. After the departure of the dragon, Mablung found Nienor in a daze upon the hill and led her away.