Somehow you’ve gotten your dream home. The cabin in the mountains, penthouse downtown, castle nestled deep in the woods, nuclear bunker in the hills, or whatever. Whats the bit you’d add that might raise a brow from others? The fireman’s pole? The slide? The moat? The hidden room behind a bookshelf where you keep your stuffed animals?
A tunnel, as in a disused railway tunnel. Could build in it - rooms, short corridors, leading to other rooms, other corridors - on and on as long as money and cheap building materials allow. Fill it with disturbing symmetries: same objects in the same places over and over. Maybe a giant isopod in formaldehyde.
Too much of Stephen King? ;-)
Although I love the idea, I’m pretty sure that if I visited you I’d never be seen again.