How to Build a Sky Fortress in Minecraft

Building upward

Build up to your sky fortress. Build a tower with ladders up to the height you want your sky fortress to be. The tower here doesn't have to be made of anything fancy, though if you want to keep it, it should probably match the material of your sky fortress. In creative mode, ladders are not necessary. In survival mode, they are the only way to get to the top!

Make the floor. Choose how wide and long you want your floor to be, what you want it to be made of, and get building. This is by far the hardest step, though it is far easier in creative mode. If you have cheats enabled, type "/gamemode 1" to go into creative mode, and "/gamemode 0" to go back into survival.

Build the walls: Build the walls of the fortress. If you build it up 2 blocks at a time, it will save a lot of falling damage. A wall that is four blocks tall, with a ceiling one block above that, will feel very spacious.

Build the ceiling. Again, this is much easier in creative mode, particularly if your walls are tall.

Build more floors to your house. If you want to have that really spacious feel, or to separate different stuff, or just to have multiple floors, then repeat steps 3 and 4 on top of the roof of your current fortress, as many times as necessary.

Decorate! Your sky fortress is now ready to be filled with both useful and decorative items. You can set your spawn in your fortress if you have a bed, which will save a lot of going up and down the ladder.

Floating Fortress

Build a floor. Make the floor as big as you want, but bigger floors increase the work load immensely.

Build your walls. Walls are a must-have for any house. Build these anywhere from 2 blocks tall to 4 or 5 blocks tall if you are in survival and want to save effort.

Build a ceiling. Just build a one-layer ceiling on the top of the house. This is a lot easier in creative mode. Add more floors. You can use the ceiling for the floor of the next story.

Mine! Mine away a lot of the area around your house, or if you built it on a hill, mine away the hill.

Make a path to your house. Your house may be great, but if you can't reach it, what was the point of making it? You can make a walkway from a nearby hill, mountain, or a ladder, or some combination of the two.