Thomas Properties Group has acquired, on behalf The California Teachers' Retirement System, Eleven Penn Center, a 29-story, 685,000-square-foot Class A office tower in the heart of downtown Philadelphia. The sale price has not as of yet been disclosed. Located at 1835 Market Street, the building is two blocks from Thomas Properties' signature office towers, One and Two Commerce Square. The building was constructed in 1987 by the Radnor Corporation, who at the time a subsidiary of Sun Company. Its 25,000-square-foot floor plates allow for flexible and efficient space configurations. Its premier tenants include TIAA CREF, Credit Suisse First Boston, Buchanan Ingersoll, Harvey Pennington and Dow Jones & Company. With the acquisition of Eleven Penn Center, Thomas Properties now owns or manages three million square feet of commercial properties in Center City Philadelphia. Its local management and leasing team will assume responsibility for Eleven Penn. A brokerage team led by Douglas G. Joseph, Brian J. Campbell, George Cauffman and Joe Fox of CB Richard Ellis, were the agents who negotiated the Agreement of Sale between Thomas Properties Group and the seller, 11 Colonial Penn Plaza Association. CB Richard Ellis had been the exclusive leasing and managing agent for the building since 1994.