On the northeastern outskirts of town, this pristine regional park is best known for a little circle of stone markers in Ball's Bluff National Cemetery, the nation's second-smallest national cemetery. It holds the remains of 54 Union soldiers -- only one identified -- who fell in the Battle of Ball's Bluff, a Confederate victory in October 1861. Many more Union troops were shot dead as they scrambled down the bluff toward the Potomac River and safety in Maryland. Many of their corpses slid into the river and floated down to Washington, bringing the grim realities of the war to the nation's capital. The park has hiking trails and interpretive displays, and volunteers lead guided tours of the battlefield on weekends from May through October. Note: There are no public restrooms here.