Lockkeeper's House: what's nearby, how to get there and when to go · 2026

The Lockkeeper's House, C & O Canal Extension is the oldest building on the National Mall, built in 1837 at what is now the southwest corner of 17th Street, NW and Constitution Avenue, NW, near Constitution Gardens.The building dates to a period when the south end of 17th Street, NW was a wharf and Constitution Avenue, NW was the location of a section of the Washington City Canal, which connected the Potomac and Anacostia rivers.