Eleven aqueducts were built from Georgetown to Cumberland to carry canal water over large streams and rivers flowing into the Potomac River. These literal water bridges carried the canal across waterways, and this aqueduct enters directly into the lock, the only one on the canal to do so. The Seneca Creek Aqueduct, or Aqueduct Number One, Lock 24, and the lockhouse were built of Seneca Red Stone quarried nearby. The same distinctive sandstone was used to construct the Smithsonian Castle on the Washington Mall. The Riley family lived in the lockhouse for many years, and after John Riley died, Mrs. Riley took over duties as lockkeeper and served here for more than 45 years. A canal boat entering Seneca Aqueduct is carried over Seneca Creek.