Minecraft wiki entry for Ancient_City, associated text: An ancient city features a very large palace that stretches throughout a deep dark biome. The palace is made up of long corridors with gray wool floors to prevent vibrations as well as some smaller ruins off to the side of the main corridors, which contain between one or two loot chests. The city center features a frame resembling a warden's head, where there are reinforced deepslate blocks, which is an unobtainable material in Survival mode. Other unique blocks such as soul lanterns and candles as well as different forms of deepslate can be found here.