Minecraft:Nether Fortress

Template:Redirect Template:Infobox structure Template:Relevant tutorial A Nether fortress is an uncommon large Minecraft:structure made of Minecraft:Nether bricks found in Minecraft:the Nether, consisting of bridges, corridors, and towers. Nether fortresses are the only place where Minecraft:wither skeletons and Minecraft:blazes spawn. They also contain Minecraft:Nether wart.

Generation

Nether fortresses generate in all Minecraft:Nether biomes. To do so, the game splits the Nether into regions in which one of either a fortress or a Minecraft:bastion remnant can generate. The regions are 432×432 blocks Template:In and 480×480 blocks Template:In.

File:Java Nether Structure Generation1.png

The Nether structure generation Template:In. The black lines represent each region and the dots represent coordinates. The green color is where they can generate and red is where they cannot.

Each region has a four chunk separation located on the south and east borders of the region in which neither a fortress nor a bastion can generate.

File:Bedrock Nether Structure Generation.png

The Nether structure generation Template:In. The black lines represent each region and the dots represent coordinates. The green color is where they can generate and red is where they cannot.

This leaves only a 368×368 block section Template:In or 416×416 block section Template:In where a structure can generate.

Two structures never generate in the same region, although they might overlap if they generate close to the separation border. The chance of a fortress attempting to generate instead of a bastion is Template:Frac (40%) Template:In and Template:Frac (33.3%) Template:In. However, if a bastion attempts to generate in the Minecraft:basalt deltas, a fortress generates instead, resulting in fortresses being the most common in the basalt deltas.

Nether fortresses can generate buried in Minecraft:netherrack. In such a case, the interior is not filled with Minecraft:netherrack; all hallways and passages are clear except for open walkways and bridges. It is possible but rare for Minecraft:glowstone or crimson and warped Minecraft:huge fungi to generate inside the fortress pathways.

Structure

Template:Main Nether fortresses are large complexes composed of Minecraft:Nether bricks supported by pillars that tower high above the Minecraft:lava seas.

File:Enclosed Fortress.png

Segments of a Nether fortress that are fully enclosed.

The fortress generation starts with a plain four-way crossing centered at chunk coordinates 11, ~, 11 of the designated Minecraft:chunk.

File:Nether Fortress Crossroad.png

A crossroad found where walkways intersect.

A fortress has two areas, an exterior area of open bridges and an interior area of enclosed corridors. Both the bridges and corridors can end in an unfinished passageway structure or may simply end without elaboration. Fortresses can tunnel through Minecraft:netherrack, giving the "exterior" areas an appearance of tunnels with Nether brick floor and Minecraft:netherrack walls and ceilings. At broken sections the terrain is not cleared, which may create a tunnel that leads straight into a wall of Minecraft:netherrack.

File:Blaze Fortress.png

The general pattern of the walkways.

File:Nether Brick Well.png

A lava well found inside a Nether fortress.

The exterior consists of:

• Straight bridges.
• Up to five plain four-way crossings.
• Up to four four-way crossings with arches made of Nether brick and Nether brick fences.
• Up to four small rooms with a single entrance and full-block "stairs" leading to the roof, which may have a single path leading out.
• Up to 2 blaze monster spawner platforms: structures consisting of three full-block "stairs" leading to a small platform fenced with Nether brick fence, with a Minecraft:blaze Minecraft:monster spawner in the center.

File:Nether Fortress Large Stairs Room.png

Stairs in a Nether fortress, with Nether wart growing next to them.

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. Rooms include:

• The lava well room, which is the connection between the interior and exterior areas.
• Straight corridors.
• Up to five four-way crossings.
• Up to 20 corridor turns (10 right-turns and 10 left-turns), each with a Template:Frac chance of having a loot chest in the corner.
• Up to three stairways made from actual stair blocks, leading downward.
• Up to two three-way intersections with a small exterior balcony.
• Up to two stairways leading up to a garden of Minecraft:soul sand and Minecraft:Nether wart at the base of the stairs, a corridor leading away from the upper landing and a corridor behind the stairs. If the room is generated embedded in netherrack, only one block above the landing is cleared, with a further indent finishing above the stairs.

File:Nether fortress corridor crossing "area bounding blocks".png

An outline of the "bounding boxes".

Blocks

Block
Template:BlockLink
Template:BlockLink
Template:BlockLink
Template:BlockLink
Template:BlockLink
Template:BlockLink
Template:BlockLink
Template:BlockLink

Bounding boxes

The structure bounding box for the 4-way intersection is pictured above (top-down view), and consists of a 19×11×19 volume centered on the floor block in the center of the intersection. This contrasts many of the other structure bounding boxes as their outlines tend to tightly follow the physical bounds of the structure. Notably, this also means that the fortress supports, which generate outside of that volume and go down to the ground and often into the lava ocean, are not considered part of the fortress for spawning purposes.

The area bounding box is a rectangular box that covers the entire fortress (again, excluding the supports). This is simply the smallest rectangular bounding box that can hold the bounding boxes of all structure pieces in the fortress.

Mobs

Fortresses use a list of possible Minecraft:mobs to spawn that is separate from the rest of Minecraft:the Nether, regardless of the biome the fortress generates in. This includes Minecraft:zombified piglins, Minecraft:skeletons, and Minecraft:magma cubes, as well as two exclusive mobs not found anywhere else: Minecraft:blazes and Minecraft:wither skeletons.

File:Nether Fortress Blaze Spawner.png

A blaze monster spawner generated in the Nether fortress.

Mobs spawn at a much higher rate if the fortress is surrounded by Minecraft:soul sand valley or Minecraft:warped forest biomes, as hostile mobs in these biomes spawn much less frequently, allowing more hostile mobs to spawn in the fortressTemplate:Only<ref>Template:Bug</ref>.

Java Edition

Template:IN, the spawning algorithm has two checks:

1. It checks if the spawn coordinates are within the "bounding box" of a single piece (e.g. corridor or walkway) of the fortress. ^{(referred as "structure bounding box" above)} In this case the block type of the ground does not matter.
2. It checks if the spawn coordinates are within the "bounding box" ^{(referred as "area bounding box" above)} of the entire fortress and whether the ground consists of Minecraft:Nether bricks (not Minecraft:Nether brick slabs).

If either check passes, it uses the special mob list for fortresses rather than the list for the biome when choosing the mob to spawn. The actual mob spawning proceeds as normal for the mob chosen from this list.

Bedrock Edition

Template:IN, instead of spawning anywhere within a structural bounding box, most mobs spawn only in structure spawn locations along varied-length lines spaced apart 4-11 blocks throughout the fortress. They are not set to a particular Y level other than "inside the structure" and are indeed columns several blocks high. They do not require any special type of block, any regular spawnable block suffices.

To identify these spawning columns, glass panes or iron bars can be placed all over the fortress, 1 block above surface blocks. This keeps the mobs stationary. (This technique works in Bedrock because structure spawns occur in the northwest corner of blocks.) Note that these spots may be on top of the raised side blocks, so these side blocks have to be removed before a glass pane grid can be placed.

Loot

File:Nether Fort Chest.png

A chest that generated in a Nether fortress.

Fortresses generate Nether fortress loot with chests in the indoor sections placed at some corridor turns.

Data values

ID

Template:El: Template:ID table Template:ID table

Template:El: Template:ID table

Config

Template:El:

<section begin="config" />

• Template:Nbt Structure configuration
  • Template:Nbt: Template:Cd
  • Template:Nbt inherit/structure

<section end="config" />

History

Trivia

• In rare cases, a fortress may not generate any indoor rooms except one single lava room<ref>Template:Bug</ref>. This usually occurs when a portion of the exterior section of the fortress blocks the exit to the interior section of the lava well room.
• Sometimes, two or more fortresses can generate close to or even within one another, creating an even larger cumulative fortress.
• There is an opening out of the fortress under the lava well, with a single block of Minecraft:Nether bricks from which the Minecraft:lava spreads out.
• The soul sand valley Minecraft:bone blocks and Minecraft:basalt pillars (down to within three blocks as-usual of a walkway) can replace more Nether bricks. Less-often, Minecraft:huge fungi, Minecraft:Nether wart blocks, Minecraft:warped wart blocks, Minecraft:crimson stems, and Minecraft:warped stems can replace Nether brick, most visibly along walls.
• A fortress can be seen in the background in the Nether in Template:AMCM.<ref>Template:Tweet</ref>

Gallery

Screenshots

• Overview of a Nether fortress with bridges and a blaze spawner
  Overview of a Nether fortress with bridges and a blaze spawner
• Some Nether warts found at a stair.
  Some Nether warts found at a stair.
• A large amount of corridors. Notice how corridors do not develop arches in their supports.
  A large amount of corridors. Notice how corridors do not develop arches in their supports.
• The long tunnels that can generate if the bridges are buried
  The long tunnels that can generate if the bridges are buried
• The lava well room.
  The lava well room.
• A fortress in a Minecraft:warped forest biome.
  A fortress in a Minecraft:warped forest biome.
• A fortress in a Minecraft:crimson forest biome.
  A fortress in a Minecraft:crimson forest biome.
• A fortress in a Minecraft:basalt deltas biome.
  A fortress in a Minecraft:basalt deltas biome.
• A Nether fortress in a soul sand valley
  A Nether fortress in a soul sand valley
• The balcony of a Nether fortress
  The balcony of a Nether fortress
• A large Nether fortress seen from the lava sea
  A large Nether fortress seen from the lava sea
• A flying Minecraft:blaze ready to attack.
  A flying Minecraft:blaze ready to attack.
• View of the blaze spawner
  View of the blaze spawner
• A Minecraft:blaze and a Minecraft:wither skeleton next to a blaze Minecraft:monster spawner.
  A Minecraft:blaze and a Minecraft:wither skeleton next to a blaze Minecraft:monster spawner.
• A blaze monster spawner room surrounded by netherrack.
  A blaze monster spawner room surrounded by netherrack.
• Firing blazes
  Firing blazes
• Two fortresses in very close proximity
  Two fortresses in very close proximity
• Minecraft:Ari spying on a fortress using a Minecraft:spyglass.
  Minecraft:Ari spying on a fortress using a Minecraft:spyglass.
• Crimson fungi inside a fortress
  Crimson fungi inside a fortress
• Warped fungi inside a fortress
  Warped fungi inside a fortress
• A ghast that has spawned inside of one of the larger rooms.
  A ghast that has spawned inside of one of the larger rooms.
• Minecraft:Fossils on a Nether fortress
  Minecraft:Fossils on a Nether fortress
• A basalt Minecraft:delta inside a Nether fortress
  A basalt Minecraft:delta inside a Nether fortress
• A basalt pillar on a fortress bridge
  A basalt pillar on a fortress bridge

Mojang screenshots

• The first screenshot of Nether fortress.
  The first screenshot of Nether fortress.
• A brightened version of the previous screenshot.
  A brightened version of the previous screenshot.
• The second screenshot, showing a large complex of the Nether fortress.
  The second screenshot, showing a large complex of the Nether fortress.
• The second screenshot brightened.
  The second screenshot brightened.
• A Nether fortress in the overworld.
  A Nether fortress in the overworld.

Historical screenshots

• A demonstration of the pathway architecture and its ability to cut through netherrack.
  A demonstration of the pathway architecture and its ability to cut through netherrack.
• A player in a fortress with another Nether fortress across from it.
  A player in a fortress with another Nether fortress across from it.
• A fortress with another one generated on top of it
  A fortress with another one generated on top of it

In other media

• A nether fortress as it appears in Template:MCD
  A nether fortress as it appears in Template:MCD
• A nether fortress as it appears in Minecraft:Sonic Racing: CrossWorlds.
  A nether fortress as it appears in Minecraft:Sonic Racing: CrossWorlds.