Located just across the river from Downtown Washington D.C. is a great multi-use recreation trail. Nearly 18 miles long, the Mount Vernon Trail follows the Potomac's Virginia shoreline from Theodore Roosevelt Island (near Rossyln, Va) to George Washington's Estate located at Mount Vernon. The Mount Vernon Trail is a big favorite of area cyclists. The trail offers wonderful views of the Potomac and DC monuments. There are also several points-of-interest along the way, including George Washington's home at Mount Vernon, Olde Town Alexandria, Arlington National Cemetery, and the local's favorite Gravelly Point (at the north end of National Airport's main runway). The trail is some what tricky to follow as it passes through Alexandria because there are actually two route choices, both of which are on street. The more popular route is along the waterfront, via Union Street. There are several shops and restaurant around the King Street intersection. However, some may find that North Royal Street provides a more direct route. Either street route is quite bicycle friendly.
