"Seneca Aqueduct \u2014 or Aqueduct No. 1 \u2014 carries the Chesapeake and Ohio Canal (C&O) over Seneca Creek in Montgomery County, Maryland. The C&O built eleven aqueducts along its 184.5 miles (296.9 km) length. Seneca Aqueduct is a unique structure, not only being the first built, but also the only red sandstone aqueduct on the C&O\u2212and the only aqueduct that is also a lock (Lock 24, or Riley's Lock). It is located at the end of Riley's Lock Road in Seneca, Maryland."@en . "Seneca Aqueduct"@en . . "1978-11-15Z"^^ . . .