Minecraft wiki entry for Door-based_iron_golem_farming, associated text: This design uses offset stacks of villages allowing players to compress a large number into a relatively small space (27 villages in less than 150 sq blocks). It is highly efficient and requires relatively low amount of resources to build. It does not require any redstone to build nor does it have to be built at spawn. The only limiting factor (as with any iron farm) is that it must be built at least 64 blocks from any other village.