This national park is a 184.5 mile dirt and stone path runs along the C & O Canal. Here, visitors can walk, run, hike, bike, rock climb, paddle, or camp from Georgetown all the way to Cumberland, Maryland. Not only is the path a great place for recreation, but there are many historic sites along the path including a 19th century stone cutting mill at mile marker 22.8. It is also home to over 200 rare and threatened species of plants.