Minecraft wiki entry for Mining, associated text: Central hub is under an area of flat ground, dig three deep holes where torches will go, ladders go on the bottom and top, torches in the middle, players go above the hub as normal only there will be a 2 high gap under the hangs on this first hub to allow for the ladders as a way up. The player will need the ladders to go all the way down, and such won't have a place for a torch. They can circumvent this by putting them on the middle of part left over at the top of the next section, the lighting is the same and players won't need an extra torch to prevent mobs spawning. This also works particularly well if they want to replace the top with glass.