The O'Reilly Theater is a 650-seat theater building, opened on December 11, 1999, in Pittsburgh, Pennsylvania. Located at 621 Penn Avenue in downtown Pittsburgh's Cultural District, the O'Reilly Theater is actually a three-part building: The 65,000 square feet (6,000 m²) theater (with a 150-seat rehearsal hall), a large parking garage called Theater Square, and the adjacent 23,000 square feet (2,100 m²) Agnes R.