Centre Square, in the heart of Center City, has been sold in the largest transaction by square footage in Philadelphia's history.

New York-based Nightingale Properties purchased Centre Square, which is made up of two Class-A office buildings totaling 1.8M SF, from Chicago-based Equity Commonwealth for $328M, according to CBRE. The property sits at 1500 Market St., across the street from City Hall and on top of one of the most heavily trafficked subway stops in the city. CBRE brokered the sale, and will be the exclusive leasing agent for the buildings.

In terms of dollar amount, Brandywine Realty Trust's sale of the former 30th Street Post Office Building to Korea Investment Management Co. for $354M in early 2016 still holds the city's record. But unlike that building, which is mostly occupied by the IRS on a long-term lease, Centre Square has a diverse tenant base — which allows for an opportunity.

Nightingale Properties has announced plans for extensive renovations on the 36-story East Tower and the 43-story West Tower, both of which were built in 1974. If it sells the buildings after such improvements, much like it did with 1700 Market St., the corresponding rent increase combined with the location could make it the priciest office transaction ever in Philly.