The Winchester Mansion, built more or less continuously by Sarah Winchester from 1886-1922 is a huge sprawling complex with with 40 bedrooms, 47 fire places, and quite a bit of surrounding mystery.  With no master plan the house has strange dead ends, doors that open onto nothing, and stairways that go nowhere.  It also is rumored to be filled with the spirits of those killed by the Winchester family's most famous product, the Winchester Rifle.