The Hallow of Eru was the summit of Meneltarma that was revered as a shrine to Ilúvatar on the island of Elenna.
The Hallow of Eru was a sacred and holy shrine that was revered by the Númenóreans. It was the only place of reverence in Númenor before the coming of Sauron. The shrine was sacred to the Númenóreans as a holy place devoted to Eru Ilúvatar. Unlike Meneltarma, no one was allowed set foot upon the Hallow of Eru. The tradition was so strong and universal that even foreigners felt bound by it. Only the King was allowed to be at the shrine to utter prayers and thanksgivings to Eru Ilúvatar, during the feasts of Erukyermë, Erulaitalë and Eruhantalë.
Birds and animals did not approach the site, and only the Eagles of Manwë were seen circling over the shrine.
Near the summit of Meneltarma, the kings had built a spiral road leading to the shrine, beginning at the southern tip of the mountain and winding up to the lip of the shrine.
The shrine was flattened and somehow depressed, which was so broad that it was able to contain a great multitude during religious ceremonies. It was said that on a clear day the 'far-sighted' might see Tol Eressëa.
During the reign of the king Tar-Ancalimon the Númenórean people grew proud, wishing to set eyes on the undying lands, despite the Ban of the Valar. Those who remained true to the Valar, the Elendili (Elf-friends), were scorned, dividing the kingdom into two parties, the faithful (the lesser party), and the King's Men (the greater party). In this time, all that kept the people from revolting was their fear for the lords of the west.
After Ancalimon' rule, the offering of the first fruits to Eru was neglected, and the relations with Gil-galad's people was forgotten, the faithful alone entering the elven lands in the north. Even the eagles of manwë ceased to circle the mountain, returning to Valinor across the sea.
After the destruction of Númenor, some amongst the Exiles of Númenor believed that the Hallow of Eru remained as an isle in Belegaer. Some Dúnedain were even said to have set sail trying to reach the isle, from which the legend held that one could catch a glimpse of the unreachable Aman.