When I was a kid we used to hop on our bikes and ride down River Road from Shepherdstown, You would ride until you saw the old ruins of a factory.
Pack Horse Ford if you are a civil war expert.

We would wade/walk out on the rocks catch a whole bunch of hellgramites, and fish all day.
Smallmouth Heaven! Suprisingly the Potomac River is very diverse river once you get out of the Heavily populated areas. Bass, Walleye, Muskie, Cats and an occasional Trout can be caught, in the right areas.