I have been in a few home dungeons. I can think of 2 fairly comprehensive ones.
The first one, a man Libertine and I know, converted the entire basement of his large suburban house. He had 12000 pounds of stone trucked in so he could make the walls look like a real dungeon. He has a separate room fitted out as a cell with a barred door and/or (maybe both, I forget) a blackout/sensory deprivation room. He's got huge beams everywhere with suspension points, and metal shackles all over the walls. He also has a set of stocks, spanking bench, and a couple other bits of dungeon kit, as well as a giant wooden dining table for D/s dinner parties with a suspension point over it. Upstairs, in his own bedroom he has a bondage frame bed with a cage underneath.
Here's a photo of a bit of the dungeon.
The second, another friend of ours, has a 20-acre rural property, on which there is a big standalone barn (formerly used as a garage) he's filled with all manner of bondage frames, stocks, spanking benches, medical kit... you name it, he's either got it or plans to build it. The building also has a couple suspension points, one fitted with a hydraulic lift. He's also got another hydraulic lift point rigged outdoors, for suspensions. As far as what in his actual house, he's got a massive hand-built bondage frame bed and a suspension point in his bedroom too.
Both these guys built most of their kit themselves, in the case of the first one, even the walls! They have met, and they are both EXTREME perfectionists. I wouldn't say they are friends...
I have to admit I prefer the granite dungeon to the garage for appearances, but I like the outdoor hydraulic suspension lift of the garage one. Here I am dangling on it, just hanging out with Libertine, whose arm is in the left side of the shot adjusting a rope.
I think after this we all went to IHOP...
So my dream home's dungeon will be designed by Dungeon Owner Number 1- and the kit built by Dungeon Owner Number 2!