Minecraft wiki entry for Building_a_metropolis, associated text: For most themes, the easiest location to build would be somewhere that is generally flat as it removes the need to clear-out large areas. Such an area can be found through a variety of ways including finding a generally-flat biome (such as plains and oceans) or loading a different world type such as superflat or buffet. The player could also use a third-party program such as WorldEdit, MCEdit, VoxelSniper, and WorldPainter to clear an area. The theme may work best in specific biome and the terrain generations, and as such, the player will need to consider those things while finding/preparing an area.