PHILADELPHIA (AP).- A post office in a building that Benjamin Franklin once owned is on the Postal Service’s list of branches that could close. The post office in Philadelphia’s historic Old City neighborhood is the only one in the country that doesn’t fly a U.S. flag. That’s because there wasn’t one in 1775, when Franklin founded what has evolved into today’s Postal Service. There’s also a postal museum upstairs from the so-called B. Free Franklin Post Office, located in a house once owned by Franklin. It opened as a U.S. post office in 1975, the 200th anniversary of Franklin’s appointment by the Continental Congress as the country’s first postmaster general. The only Colonial-themed post office operated by the Postal