Nether Fortress

Nether fortresses are structures that are naturally generated in the Nether.

Generation


Nether fortresses tend to cluster together in strips that run along the Z-axis (north and south). Players who travel along the X-axis (east or west) will have the best chances of finding one; those who travel north or south may travel for hundreds or thousands of blocks before discovering a fortress.

Nether fortresses may be generated in inconvenient places, where half of or even the majority of the fortress is buried in netherrack. The interior will not be filled, however; all hallways and passages will be clear except for open walkways and bridges. It is rare, but possible for glowstone to generate inside of the fortress pathways.

Mobs


Nether fortresses use a separate list of possible mobs to spawn, separate from the rest of the Nether. Nether fortresses spawn magma cubes at a much higher rate, and also spawn two exclusive mobs which cannot be found anywhere else: blazes and wither skeletons. Normal skeletons have a 20% chance to spawn in place of a wither skeleton. Ghasts are not allowed to spawn to prevent them from being trapped inside and suffocating.

Blazes are desired because of their main loot - blaze rods, as well as the high amount of experience they drop. Wither skeletons are mostly desired for their wither skeleton skulls, which are necessary to create the wither.

The spawning algorithm has two checks: If either check passes, it uses the special mob list for nether fortresses rather than the general list for the Nether when choosing the mob to spawn. The actual mob spawning proceeds as normal for the mob chosen from this list.
 * 1) It checks if the spawn coordinates are within the "bounding box" of each piece (e.g. corridor or walkway) of any fortress.
 * 2) It checks if the spawn coordinates are within the "bounding box" of the entire fortress, and that the block under the spawn location is nether brick.

Structure


Nether fortresses are very large bridge-like complexes, composed mainly of nether bricks, that are supported by massive pillars that tower high above the lava oceans, and are topped with long catwalks stretching for dozens of blocks, the ends of which may be broken. Nether fortresses can tunnel through netherrack, and the inside of the tunnels will be cleared of netherrack by the terrain generator. However, at broken bridge sections, the terrain is not cleared, which may create a tunnel that leads straight into a wall of netherrack.

The interior of the structures have 1×2 windows with nether brick fences as the windowpanes. The fences also form gate-like structures at the entrances of some rooms and corridors.



The interior is also comprised are a fair number of different rooms, including:
 * 3-block-wide hallways
 * Lava well rooms, which are the single connection between the indoor and outdoor sections
 * Rooms with nether brick stairs in the center and soul sand at the sides, with two 2×5 rows of nether wart growing on it.
 * Rooms with blaze spawners (normally 2 per fortress), which can have nether brick stairs leading up to them. The rooms also have nether brick fences.
 * Rooms with four exits. Some of them lead only to netherrack.
 * Rooms with a "stairway" of nether brick placed against a wall, leading up to the floor above.

Loot


Nether fortresses generate nether fortress loot with chests in the indoor sections placed at some interior points where corridors turn at right angles.

Trivia

 * Often, nether fortresses spawn with no nether wart gardens in them at all. In some rare cases, a garden will have spawned, but the nether wart will be partially or totally destroyed by falling lava.
 * In extremely rare cases, a nether fortress will not generate any indoor rooms except one single lava room.
 * Sometimes, two or more nether fortresses can spawn very close or even within each other, ultimately creating an even larger cumulative nether fortress.

Gallery
Netherfestung Fortaleza del Inframundo Forteresse du Nether ネザー要塞 Nether Fort Forteca Netheru Адская крепость 下界要塞