Woodland Mansion

A woodland mansion is a massive systematically-generated structure found in dark forests, often far away from the world spawn point. A mansion is inhabited by evokers, vindicators and allays, and is one of the few places where a totem of undying can be obtained, aside from raids. Besides illagers, a mansion's interior lighting is sufficiently low for other Overworld monsters to spawn.

Generation
Woodland mansions typically generate thousands of blocks from the spawn point. They can be located with woodland explorer maps, which are obtained from cartographer villagers, but a map may not always point to the nearest one. The nearest woodland mansion may also be located via the command enabled by cheats. A dark forest biome with a woodland mansion is rarer than a mushroom fields biome, as 32 blocks of dark forest must surround all sides of a woodland mansion's point of generation.

Mobs
A woodland mansion naturally generates vindicators, evokers, and allays inside the mansion, but because the entrance is open and most rooms in the woodland mansion are dark, Overworld monsters sometimes spawn in these rooms or come in through the entrance at night.

The first floor of the mansion may only generate rooms that contain vindicators; from the second floor upward, some large rooms may contain both evokers and vindicators. Neither type of illager spawns directly in the hallways of the mansion, but they often wander into the hallways after spawning in.

Once all the vindicators and evokers are killed in a woodland mansion, they do not respawn, unlike pillagers, who respawn when all of them are killed in a pillager outpost.

Structure
Although their exact structure varies, all woodland mansions have some things in common: they all have three floors with a variety of rooms, and generate a cobblestone foundation underneath the entire structure if there are any gaps between the bottom of the mansion and the ground. The top floor is about half the size of the lower floors, but the size of each top floor is pretty random for each mansion, depending on how many rooms are going to be generated on the top floor. Each mansion includes a large foyer that leads to the corridors connecting the rooms, a giant staircase also generates there, which leads up to the second floor. The foyer is dark and many hostile mobs spawn under the staircase.

Rooms
A woodland mansion contains many types of rooms. Because the layout is randomly generated, some room types may not be present. Furthermore, certain rooms within the mansion are not readily accessible – some may have sealed entrances, while secret rooms have no entrances at all.

One may access the individual structures of a woodland mansion by using structure blocks to manually load room structures from the  folder in minecraft.jar. To do so, set a structure block to Load mode, enter, and press LOAD. A list of possible rooms, the names of these structures, and small descriptions are provided in the table below. Note that the room names are conjectural.

Main and secret rooms
A woodland mansion sometimes generate secret rooms on each floor. A secret room can be one of the following type: "X" room, spider room, fake end portal room, obsidian room, birch pillar room, clean chest room, lava room, and attic room, with the 'X" room being the most common, and the "lava" room being the rarest. A way to look for a secret room is looking for gaps between normal rooms, this way is the best on the first floor, as there are no windows. Another way is looking through the windows through the second and third floors of the mansion, since some secret rooms are exposed to windows. A last way to look for a secret room is cutting down the roof, which works best for the third floor alone. Then you can see any secret rooms from the roof of the floor, as the whole floor's layout.

In the table below, a indicates either a chest with random loot, or the spawn point of an illager.

Trivia

 * Woodland mansions were added as a way to implement illagers, the main antagonists of the then-developing game Minecraft Dungeons, into the base game of Minecraft, providing them with a place to live.