Annapolis Rock, a ca. 50 minute, 2 mile hike up the Appalachian Trail in the backcountry of the South Mountain Recreation Area (South Mountain State Park), is a terrific, short band of western facing cliffs 1800 feet above the Cumberland Valley and Greenbrier Lake near Frederick, MD. The rock is bullet-hard quartzite characterized by smooth bulges and long, horizontal fractures. It's a great Maryland area for TRing and Trad.
The single pitch climbs are often top roped. Long (50+ ft) webbing or static line will serve to anchor to the many boulders and trees atop the cliff. A few large to medium pieces of pro may be helpful for anchoring as well.
There is a backcountry camping area, a privy, and a spring (you might want to treat the water before drinking, or maybe not) on site. The camping area seems to be heavily used.
From Baltimore take I-70 West to Exit 42, Myersville (bear right off the ramp). Follow Route 17 through town; it takes a right. At the intersection of Route 40, go left onto Route 40. After about 3 miles you will see parking by the road and a sign for the Appalachian Trail. Park here. Put on your pack and hike the AT north (following signs and white blazes) for about 2 miles. You will see a sign for Annapolis Rock at a short side trail off to the left. You've arrived.
Mountain Project's determination of some of the classic, most popular, highest rated routes for Annapolis Rock: