One of the most idiosyncratic houses in Petersburg is the brick trapezium-shaped house built by Irish bachelor Charles O'Hara. Although his three-story side-passage house resembles other Federal structures in Petersburg in most ways, it has one outstanding difference. The walls follow the trapezoidal shape of O'Hara's lot and, as a result, none of them are parallel. A local folk story has it that O'Hara was advised by a West Indian servant that this would ward off evil spirits. For years, the residence was known as Rat Castle because of the pet rats kept by the undoubtedly eccentric O'Hara.