Mary's Rock Tunnel

The only tunnel on Skyline Drive, bored 200 m through the flank of Mary's Rock just south of the Thornton Gap entrance. Blasted through solid granodiorite in 1932, it is a genuine piece of Depression-era engineering and the first thing you pass entering the park from Luray. Clearance is 12 ft 8 in (3.86 m), which rules out taller RVs.

There is a small pull-off at the southern portal with a view down the Thornton River hollow — the tunnel itself is a drive-through moment rather than a walk-around one.