Here's the photo I took of Steve on the Chesapeake & Ohio Canal towpath, just below Lock 13 and Interstate 495, on his first day. Lock 13 is at mile 9.4 on the towpath. Mile zero is in the District of Columbia near where Rock Creek flows into the Potomac River. This spot is the "tidewater lock", where canal boats entered the river - the northernmost navigable part of the Potomac. Another name was the "watergate." Just across Virginia Avenue from this spot is the apartment/office complex by the same name, unfortunately a name that now has a different historical meaning.
Best wishes for Steve's adventure!
Dixie Sommers
Alexandria, VA