PHILADELPHIA — CBRE Capital Markets has brokered the sale of Centre Square, a two-building, 1.8 million-square-foot office complex located at 1500 Market St. in Philadelphia. An affiliate of Nightingale Properties acquired the complex for an undisclosed price. Robert Fahey, Jerry Kranzel, Erin Hannan and Jack Corcoran of CBRE represented the seller, Chicago-based Equity Commonwealth, in the transaction. Built in 1974, the complex consists of a 36-story East Tower, a 43-story West Tower, a 450-vehicle parking garage and 41,000 square feet of retail space. The University of Pennsylvania Health System, Towers Watson, PHMC, Saul Ewing, Dilworth Paxson and Radian are tenants at the complex.