Ballston, VA to Silver Spring, MD
Starting at Marymount Univ. at the corner of N. Glebe Rd. and Fairfax Dr. go N. on Custis trail until Key Bridge. Cross Key Bridge to join the C&O canal trail/Capital Cresent Trail. At Bethesda join the Georgetown Branch Trail. Soon after a narrow bridge you can get on to the RockCreek Park trail. Unfortunately I missed it and wound up at Silver Spring Metro station where the Georgetown Branch Trail ends. So I took the train back home. Its a nice trip.