One of my favorite short hikes in the D.C. area, the Billy Goat Trail winds along the Chesapeake and Ohio (C&O Canal) and the Potomac River offering scenic vistas and beautiful floral and woodland surroundings. The trail lies where the actual old bed of the river used to be before the river carved the immense Mather Gorge where it now lies.
Start from the Great Falls Tavern Visitor Center. Be sure to bring water and wear hiking boots or sturdy shoes. You will have to go on hands and knees to climb over some large and inclined boulders and rock faces including a 60-foot vertical climb up the Spitsbergen Cliffs.