Trinity house.

About Trinity house

A Trinity house, also known as a band-box house or a Father, Son & Holy Ghost house, is a small townhouse, principally found in Philadelphia, Pennsylvania. Trinity houses are characterized by small size, with three or four floors vertically stacked, each usually consisting of one principal room, many of which were built in the 18th and 19th centuries. They are joined by small, winding stairways, and have few or no interior doors. The "Trinity" name is derived from three floors, three rooms. Kitchens are usually in the basement, with very low headroom. Houses are typically smaller than 1,000 square feet (93 m2), and about 14 feet (4.3 m) wide. The selection of furnishings for such houses is strictly limited by the difficulty of moving furniture between floors.