The Fulton, two blocks west of Penn Square on Prince Street, is one of the oldest continuously operating theatres in the United States. The Italianate facade dates to 1852, with a heavily ornamented Second Empire interior added later in the nineteenth century. Mark Twain, John Philip Sousa, Ethel Barrymore, and Sarah Bernhardt all performed here in its heyday.
Today it is the resident professional theatre for the region, with a year-round season of plays and musicals. Even if you don't see a show, the lobby and exterior are worth a look. Tours are available occasionally; check the schedule.