Keystone Viaduct, Great Allegheny Passage:
Bridge over the Severn River at Annapolis:
Bridge over the Chesapeake and Delaware Canal. I chose to walk through the construction area after I saw a truck take up the whole shoulder.
Oldtown/Greenspring toll bridge over the Potomac. One of the last privately owned toll bridges in the US.
Bridge on the C & O - I don't recall which one.