Known as the skinniest park in the commonwealth of Virginia, the Washington & Old Dominion Regional Park extends a total of 45 miles from Alexandria to Purcellville. The park is home to the Washington & Old Dominion Trail, a paved multiple-use bike path. A crushed stone bridle path runs alongside the trail in some areas.

The Washington & Old Dominion Trail is built on the grade of the former Washington & Old Dominion Railroad. When the railroad was abandoned in 1968, the right of way was bought by the Virginia Electric and Power Company to use for power transmission lines. For years, the Northern Virginia Regional Park Authority struggled to build a bike path on the property. In 1974, a small portion of the trail opened in Falls Church to prove whether the trail would be popular. Three years later, the park was allowed to purchase the right of way.

The bike path was finally completed in 1988, and is a popular recreation spot. The path runs from Alexandria to Arlington, Falls Church, Vienna, Reston, Herndon, Ashburn, Leesburg, and finally ending at Purcellville. Several of the stations from the old railroad still exist today. The station in Vienna is home of the Northern Virginia Model Railroaders, and the station at Herndon is currently used as a museum.