Old Red Bridge by Gallery Three Photography by Tom Gari. Thomas Mill Covered Bridge is the only covered bridge still standing within the city limits of Philadelphia. The bridge is surrounded by Fairmount Park and displays unusual sawtooth decorations. The 86.5-foot-long (26.4 m), 18.66-foot-wide (5.69 m), Howe-truss bridge was built in 1855. It was renovated by the Works Progress Administration in 1939, and by the City of Philadelphia in 2000.