South of Washington DC in southwest Fairfax County, the Fountainhead Regional Park has a 5 mile multi-use trail. This rooty trail rolls through forest. To reach the mountain biking trailhead from DC, head south on US395 to US495 west. Exit at Braddock Road. Head west on Braddock Road for 6 miles. Turn left heading south on SR123 (aka Ox Road) for 8 miles. At Hampton Road, turn right for 3 miles into the park. The trailhead is across from the first parking area.
Overall, Fountainhead Regional Park is the 10th most popular mountain bike trail of all 27 mountain biking rides in Virginia.