Carderock: Billy Goat Trail Section C + C&O Towpath loop · 2.6 mi

Carderock Recreation Area, off Clara Barton Parkway, Potomac. Park in the North Lot. Fall color along the Potomac, with rock outcrops and river views. Free parking — no entrance fee here, unlike Great Falls. Arrive early; this lot fills up. The return mile is on the towpath, which is shared with cyclists — we'll walk two abreast and keep right.