Iron Farm / Trading Hall

There are lots of iron farm / trading halls out there... This one holds 20 villagers in their own cells, is pretty simple to build, and gives good access to the villagers for trading. Additionally it optimizes the bed positions so that Iron Golems can't spawn outside the farm. In fact, no matter which bed is the "center of the village", there is enough space to virtually guarantee that every golem spawn attempt succeeds. This farm can be made in any direction. However, the bed placement may vary depending on the direction in which it is built. The beds should be offset by 1 block to the south and east sides, such that there are 8 blocks of space from northwest corner of the northwest pillow to both the north and west sides of the farm, and 7 blocks of space from the southeast corner of the southeast pillow to the south and east of the farm.