Nether Fortress



Nether Fortresses are structures that are naturally generated in the Nether. They include bridge structures constructed of Nether Bricks, Nether Brick Fences, and Nether Brick Stairs. They often contain Blaze spawners, and are the only place that Nether Warts can be found.

Nether Fortresses are comparable to the overworld Strongholds, but use different materials, do not contain End Portals and are not limited to 3 in a world.

History
Nether Fortresses were first introduced in the 1.9 Pre-Release.

Structure
Nether Fortresses are very large complexes made mainly of Nether Bricks. Nether Fortresses can often 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 flat wall of Netherrack. Their main structure takes a shape of bridges with supporting pillars outside and corridors inside, both which have 3-blocks wide walking space. The bridges can be broken at the end. The interior of the structures have 1x2 windows with Nether Brick Fences as the windowpanes. The fences also form gate-like structures at the entrances of some rooms and corridors. The rooms include:
 * Lava well rooms
 * Rooms with Nether Brick Stairs in the center and Soul Sand at sides of the stairway containing 2 2x5 rows of Nether Wart growing on it.
 * Rooms with Blaze spawners. Nether Brick Stairs can lead up to them. The rooms have Nether Brick Fences. There are normally 2 spawners per fortress
 * Rooms with four exits. Some of them could lead only to Netherrack.
 * Rooms with a "stairway" of Nether Brick placed against a wall, leading up to the floor above.

Trivia

 * Nether Fortresses are fairly safe from Ghasts, because they are enclosed (so Ghasts usually can't spawn inside or enter) and are made out of materials that Ghast fireballs can't destroy.
 * Rarely a Nether Fortress can have rooms that are large enough for Ghasts to spawn inside.
 * A common misconception is that Magma Cubes spawn more frequently in Nether Fortresses. The reverse is actually true, because the confines of the structure and the lack of large flat surfaces reduces the chances of a Magma Cube to spawn.
 * Nether Fortresses will still be generated even if the "Generated Structures" option is turned off.
 * Mushrooms can spawn in Nether Fortresses.
 * Glowstone can spawn in Nether Fortress corridors.
 * Nether Fortresses which spawn high above the lava ocean can create huge walls of Nether Brick twice as tall as Overworld mountains.
 * Nether Fortresses tend to spawn in "strips" aligning along the Z axis (north/south) in the nether, making them easier to find after one has already been found by simply moving north or south, keeping the X coordinate steady. (Tested over 200 seeds so far, the trend is strong in all tested seeds (Confirmed with AMIDST).)
 * Sometimes, two or more Nether Fortresses can spawn very close or even within each other, ultimately creating an even larger cumulative Nether Fortress.