The Lockkeeper’s House is on the edge of the Mall at 17th St. and Constitution Avenue. It was built for the lockkeeper of the C&O Canal Extension, which connected the C&O Canal to the Washington City Canal. The building was constructed in 1832 and abandoned in 1855, as the Washington City Canal stopped being used, and was filled in during the 1870’s. The house became the Park Police headquarters in the early 1900’s. Since then, it has been used for storage.