Purple Horse is located along the first and most rugged section of the Billy Goat Trail; this stretch of the popular hiking and scrambling trail travels Bear Island from Great Falls of Maryland south almost to Old Angler's Inn. Bear Island forms the eastern (Maryland side) side of Mather Gorge, and the gorge is where the best climbing crags in the Great Falls area are concentrated.
Purple Horse is alongside the Potomac River, but the climbs themselves are mostly set back from the water in normal and low-water conditions.
About 15-20 minutes from the parking area, hikers on the Billy Goat Trail pass two ponds and then arrive at a sandy beach (Purple Horse Beach) before turning to climb some rock outcrops as the trail continues upstream. The low, broad crag on your left as you reach the beach is Purple Horse Rock. The climbs here are only 25-35' and the rock is not too visually spectacular, but the crag does have a couple of nice roof climbs and a good wall on which beginners can practice. Mostly, though, Purple Horse sees scramblers and boulderers playing on its faces, cracks, and outcrops.
Purple Horse is a great place to hang out and play around or laze away a warm afternoon after you scramble or climb to a nice perch overlooking the river.
Although I've never seen any roped climbers on Purple Horse, I am still listing the named routes on it, from its upstream to its downstream end:
The Prow (5.10)-- One of the roof climbs; see attached photo.
Barn Door (5.9-)
Barn Roof (5.9)-- The other roof climb.
River Wall (5.4-5.8)-- Many options here; I scrambled something near the left end of the wall, but it didn't feel like 5.4 (more like Class 4 with one or two 5.0-5.2 moves); this page's primary image shows this wall.
Swing Low (5.10-)
From I-495, take Exit 41, just north of the Virginia line, heading west on the Clara Barton Parkway and then onto MacArthur Boulevard. About 3 miles from the interstate, look for Old Angler's Inn on the right side of the road. Across the road from the inn is a parking area. Park.
The parking area fills early on nice weekends. Do not park at Old Angler's Inn. If the parking area is full, look for roadside parking along the south side of the road or continue along MacArthur until you reach the entrance to C&O Canal National Historical Park. There is more parking here, but you have to pay a $5 admission fee, and you will also have a longer hike to the crag.
Red Tape, Camping, and Links
No admission fees if you start at Old Angler's Inn, but the area is on NPS land and all regulations for C&O Canal NHP apply (see links section).
The park closes at dark. Do not alter the rock in any way to place gear. Beware poison ivy and copperheads.
C&O Canal NPS site
An excellent resource for the area is Eric Horst’s Rock Climbing Virginia, West Virginia, and Maryland. The section on Great Falls provides one-sentence overviews of the routes. Also, consider the PATC Climbers' Guide. It focuses just on the Great Falls area and details more crags and routes than the other guide does.