Sooo I really like abandoned places and antique things. I don't exactly go so far as to break into abandoned places in order to explore them, but I definitely will hit up a museum or exhibit related to either topic. The Andén Cero is a small exhibit located in the former Chamberí metro station. (And actually they have a second little museum consisting of an "engine shed" in another part of the city that I haven't yet visited.)
Chamberí station was one of the original eight stations of the first metro line built in Madrid in 1919. The station was closed a few decades later in the 60's when the city began extending the metro lines. It was reopened as a bit of a blast-to-the-past exhibit, complete with old posters advertisement on the walls and original tiling. The place is small, but since it's free to see it's a neat little place to visit.
