A creeper proof castle that I made on one of my home servers. I first built it out of dirt as the template then dug it out while filling it in with obsidian. 100% hand built. Redstone switches can open the door on any level of the castle.

Additional Notes

The front stone steps conceal doorbell,and the diamond around the door is decoration. For security reasons the front door is only openable from the inside,but that is easily fixable with one leaver.

If you want it fully creeper/TNT proof wait for me to update it with obsidian piston door.
(this castle was built before pistons)