How far do nether fortresses extend vertically?

How far do nether fortresses extend vertically? - Brown Wooden Pathway on Forest

I'd like to build a spawning platform above the bedrock layer of the nether. If I build it over a nether fortress, will it continue to spawn wither skeletons?



Best Answer

I'd like to build a spawning platform above the bedrock layer of the nether. If I build it over a nether fortress, will it continue to spawn wither skeletons?

Um... No.
If you build your platform to go through parts of the fortress (at the height the ground of the walkway are on), then sort of; as in: Only the areas that go through the original position of the nether fortress will spawn the mobs.


The way nether mobs (other than Ghasts and Zombie Pigmen) such as Blazes, Wither/Regular Skeleton and Magma Cubes is that they spawn in specific regions within the Nether.

As for what those "specific regions" are, they are areas that are created during Nether Fortress Generation.
These areas do not extend to the borders of the chunk the Nether Fortress resides in, and they are made to only "fit"* the exact area the fortress resides in, meaning that they're anywhere from 15x15x8 (a 4-way intersection) to 7x5x7 (a single piece out of a long hallway) joined together as to how the fortress is laid out.

Mobs only spawn on a block if the block above it is within these regions.

*Exceptions apply with specific prefab sections of a Nether Fortress.


If you need some visualisation, this nifty video should clear things up by explaing how each "spawn region" covers each module of a Nether Fortress:

Note: Didn't really rewatch the video, so my numbers regarding areas may be wrong, but the general idea is still correct.




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How far are Nether fortresses apart?

There are infinite nether fortresses in the nether. They spawn in rows every 200-400 blocks along the world's North/South axis. Once you find the first one, just keep walking north or south from it to find another.

At what height are nether fortresses?

Usually Nether Fortresses is located at an altitude between 60 and 70. We will move in a tunnel 2 blocks in size so that under us there is almost always 1 block separating us from free space. But do not descend below a height of 100 without having to go out to picking Mushrooms or inspecting the terrain.

What y coordinates are nether fortress?

Nether fortresses are large complexes, composed of nether bricks materials, that are supported by massive pillars that tower high above the lava oceans. The fortress generation starts with a plain four-way crossing centered at chunk coordinates 11, ~, 11 of the designated chunk.



How to prepare a Nether Fortress for Wither Skeleton Farming [Tutorial]




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Images: Erik Mclean, veeterzy, Nout Gons, Mads Thomsen