Fort Marcy is perched 275.4 feet above the Potomac River on the south side of the road leading from Chain Bridge to Langley and McLean, Virginia. It is a relatively undisturbed fort and was named in honor of a native of Massachusetts, Randolph B. Marcy, a distinguished soldier and father-in-law and chief of state to General George B. McClellan. Park can only be entered traveling northbound on the George Washington Parkway. Out of the 68 forts built around Washington, DC during the Civil War, Fort Marcy is now one of the few to survive. Its purpose was to protect the Chain Bridge, which used to be one of the only bridges from Virginia into the District. NOTE: To access the park, you must be traveling in the northbound lanes of the GW Parkway as there is no turnoff access for the southbound lanes.