This National Park showcases the historic Fort with its unusual moat, drawbridge, high stone walls, and cannons, built by the new American nation for protection against a British invasion and used intermittently by the military until World War II. The scenery of the Potomac River shoreline is beautiful, with views across the River to Mount Vernon, Va. and northward to downtown D.C. in the distance. The park has a circular, flat roadway excellent for hiking, skating, or bicycling. There are picnic areas, fishing, a lighthouse, a small playground and basketball court. Improvements were recently made to the shoreline hiking trail (which few people know about) which follows the River from the lighthouse southward. There is a tiny bookstore and museum open limited hours. Admission is free after 5:00 until sundown, and at most times in winter. Otherwise an admission fee.