Philadelphia has a lot of bridges due to all the rivers and creeks. At least 30 on just the Delaware, schuylkill and wissahickon. A bunch of other ones that i'm not sure are more than 200 feet.
Some of the more interesting one for me are:
Ben Franklin (9650 feet)
Tacony Palmyra bridge (3695ft)
Henry ave bridge (333 foot stone arch)
Walnut lane (585 ft) different bridge than one above
Strawberry Mansion bridge (1242 feet)
Falls bridge, which is due for some tlc but still pretty cool (556 feet)
Market Street bridge
I assumed we weren't included train bridges, but what about pedestrian/bike? In that case I'd add manayunk bridge: (1900 ft)
And the new schuylkill river trail bridge
Some nice lost bridges replaced by generic looking ones:
Girard ave bridge:
Chestnut street
Spring garden/callow hill bridge