Ancient City

An ancient city is a palatial structure found in deep dark biomes at layer -52, harboring chests containing some items that cannot be found anywhere else.

Environment aesthetics
An ancient city features a very large palace that stretches throughout a deep dark biome. The palace is made up of long corridors with some rugs made of blue, light blue and cyan wool or carpet 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 has statues and the 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 and sculk can be found here.

Some structures resemble elements of the game. The city center bears a resemblance to early iterations of the warden's design, and other structures resemble pillager outposts and woodland mansion rooms.

Overall view
The following three renders are the same instance of ancient city.

Redstone circuits
Underneath the frame at the city center lies a series of hidden basements with naturally generating redstone circuitry.

The secret entrance is located at the base of the structure, underneath the wooden bridge between the city center and the wall. There's a piston door that is controlled by a sculk sensor in the Redstone circuits in the basement.

File:Ancient city basement 1.png|Basement of. File:Ancient city basement 2.png|Basement of. File:Ancient city basement 2 2.png|Furnace in the basement of. File:Ancient city basement 3.png|Basement of. File:Ancient city basement 3 2.png|Piston door circuit in the basement of.

For city_center_1, there is a chiseled deep slate in front of the frame, making a vibration around it that can activate the sculk sensor and then open the piston door. There's also a fader pulse extender between the sculk sensor and piston door, which makes the piston door close 180 game ticks after the sculk sensor is deactivated.

The circuit in city_center_2 is similar to the former, but with a signal strength filter. Only vibrations with a frequency equal to 8 (mob interactions, projectile hits, eating, entity damage) can activate the piston door. Creating these vibrations on the path in the front of the frame in the city center activates the door.

For city_center_3, making a vibration on the path in the front of the frame on the city center can activate the sculk sensor. Additionally, there's a T flip-flop between the sculk sensor and piston door. After the sculk sensor is activated, the piston door remains open until the sculk sensor is activated again.

There are three basic Redstone circuits in the basement:

File structure
All ancient city structures found below are located in the folder client.jar/data/minecraft/structures/ancient_city, data/structures/ancient_city.

Loot
The loot in the chests includes several useful items for exploring the ancient city, such as snowballs and the Swift Sneak enchantment, as well as items that can't be found anywhere else, such as echo shards.