The Lost Shrine is a location in NieR. It is a massive structure located in a pillar of stone within a deep crater, not far from Nier's village. The shrine may have been an apartment building or hotel from the old world, as the layout is similar to them, and rooms with appliances, such as a bathtub, can be found.
The Lost Shrine's canyon edges are lined with old world dams, suggesting that it might have also been a resort island getaway.
The shrine was in a state of disrepair due to the passage of time, as the entire upper floor was heavily damaged and the decorative tree in the center of the shrine had grown too large, damaging the spiral staircase. The upper-most level of the shrine contained both Grimoire Weiss, with his guards Hansel & Gretel, and the portal to the Shadowlord's Castle. According to Tyrann, this is where incomplete Shades tend to be located.
The Lost Shrine is the first location that the player is able to visit, outside of Nier's village. When Yonah goes missing, Nier heads to the shrine to search for her. He finds her at the top and has to fight Hansel and Gretel, awakening Weiss and gaining him as a party member.