Nether Fortress is a large structure found in the Nether, made of nether bricks and composed of bridges, corridors, and stairways. It is the only place where blazes and wither skeletons naturally spawn, making it necessary for brewing and fighting the Wither.
The structure includes blaze spawner platforms, Nether wart gardens, and loot chests placed in corridor turns. Chests can contain items like gold, iron, diamonds, saddles, and horse armor.
Separate mob spawning rules apply: blazes, wither skeletons, zombified piglins, magma cubes, and skeletons spawn at higher rates within fortress boundaries.