The Calhoun School, a private school located on Manhattan’s Upper West Side, commissioned FXFOWLE to design a four-story addition to the original five-story building. The design, which resulted in an additional 30,500 square feet of space, resolves the formal and programmatic challenges entailed in expanding vertically and horizontally to the 1973 concrete and travertine building. The expanded school contains a two-story performing arts center, with a 234-seat black box theatre as the centerpiece. Surrounded by rehearsal spaces, set design shop, and music instructional spaces, the three-quarter round theatre provides flexible performance space for the arts department and specialized teaching space for all the arts. General purpose classrooms and science labs are included too. The 5,200-square-foot gym is located on the top floor of the addition. A green roof tops the building. The school remained in operation throughout construction.