Winchester House in San Jose, CA was the home to Sarah Winchester, the widow who inherited the Winchester rifle fortune and a controlling stake of the company. It is not clear why she built the mansion, but the general story is that she felt haunted by the ghosts of those killed by Winchester rifles, and was building a home for them. Whatever the reason, the house was converted from a barn, built into a seven story mansion, and then added on to continuously until Mrs. Winchester died. There was no set plan, and everything was just haphazardly put together. Not to mention that the top three stories were lost to an earthquake.
This seems like just the sort of random, obsessive thing that speaks to my soul, so I will try to go see it some day.