Chicago-based real estate trust Equity Commonwealth is moving to sell the Center City office tower at 1735 Market St. known as BNY Mellon Center, its last remaining Philadelphia property.

Equity Commonwealth, controlled by investor Sam Zell, has engaged a team at real estate services firm HFF in Philadelphia to market the 54-story, 1.3-million-square-foot tower, HFF senior managing director Doug Rodio said Wednesday.

The tower, Philadelphia's fifth-tallest building, is 91 percent leased to tenants including Bank of New York Mellon Corp., Goldman Sachs Group, and law firms Ballard Spahr LLP and Montgomery McCracken Walker & Rhoads LLP. Rodio said his team is targeting a sale price of $500 million for the building.

The 1735 Market St. tower is the last remaining property in what had been a large portfolio of Philadelphia office buildings owned by Equity Commonwealth.

The real estate trust's former properties include 1600 Market St., once known as the PNC Bank Building, which was sold earlier this year; Centre Square, the 1500 Market St. office complex known for Claes Oldenburg's 45-foot-tall Clothespin sculpture in its front plaza; and the former One Franklin Plaza building, GlaxoSmithKline's past headquarters at 16th and Race Streets.