The Patowmack Canal, one of the earliest canals built in America, is located in Great Fall National Park. This 800-acre park has views of the falls, 15 miles of hiking trails, and 5 miles of trails for horseback and biking. Ranger guided walks. Picnic facilities. The significance of the Patowmack Canal in the development of the young nation is evident in its designation as a National Historic Landmark. The Patowmack Canal is a Civil Engineering Landmark, and a Virginia Historic Landmark.