I've been trying to remember his name for weeks now and it just hit me. Gregor Schneider is an installation artist of sorts whose major work is Haus UR, a perpetual reworking of his house in Rheydt, Germany. He would create new rooms within rooms, brick up windows, make traps and hidden doors, and then these would be carefully excised from the house and set up in galleries and museums. I went in one once, called something like "guest room" which was a concrete and wood cell with a rough cot and a door without a handle on the inside. Even though it was in a museum exhibition, you got the distinct feeling that if that door closed behind you, you would be trapped in there forever.
Here! take a tour!