Ancient City

An ancient city is a palatial structure found in deep dark biomes at Y=-51, that harbors chests containing items, such as disc fragments, armor trims and echo shards, that cannot be found anywhere else. It is also one of the only two places where sculk sensors can be found.

Ancient cities cannot generate overlapping each other; however, they can generate directly adjacent to each other.[1]

Because they can only generate in the deep dark, they will often be found under mountains and other places with low erosion.