Roundtop Hill is a mountain in Washington County, Maryland, southwest of the town of Hancock.

Unlike surrounding mountains, Roundtop Hill is not part of an extended ridge system, and is only about 2 miles (3.2 km) in length.

Its presence causes a large bend in the Potomac River, which curves around its eastern slope.

Much of the eastern face is part of the Chesapeake and Ohio Canal National Historical Park and the canal bed and tow path pass along the narrow bank at its base.

Examples of folding, formation of cleavage, thrust faulting, and the deformation of bedded rocks are visible.