This is one of my first creations since my pc broke,so i decidd to upload it...
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its relatively small but has a lot of stuff and functionalities:

a little chamber in the wall, with snow golems that can shoot zombies


it has two railway-rings situated on different levels,basic use is to put snow golems in carts and let them continuously go around the caslte and kick off hostile mobs (zombies)


has a couple of secret doors...
the side-towers can be accesed through water-gates and they dispense water from the bottom, ,so this was initially used for transportation,to and from the castle,since its floating in mid-air. One of the towers has a hidden fireball-machinegun,withretractable shutters that are hiding the dispensers.
Access to the "basement" is through a secret waterfall-door,wich leads to another redstone-generated huge door.
First level has all the basic stuff for living,like anvils,crafting table,and so on,as well as a luxury private room .
Second level has a secret storage room triggered by a lever from another level(initially i was planning to fill the chests with spawn eggs ,so that i could troll my friends on my serv,but you can use them for anything)
this level also has access to a lava-torture room,wich should be modified a bit,as its the only way to access the double-guarding tower from the bottom( i initially used them as ghast turrets but oh well nevermind)


last level has a nether portal,covered up by a 2x3 piston door.