Aqueduct No. 1, better known as Seneca Aqueduct, was begun in 1829 and completed in 1832. A unique structure on the C&O Canal, Seneca Aqueduct is the only aqueduct that is also a lock (Lock No. 24, also known as Riley’s Lock; it is named after John Riley, who ran the lock from 1892 until the canal closed in 1924). Seneca Aqueduct is doubly unique in that it is the only aqueduct made of Seneca redstone. The adjacent lockkeeper’s house was finished in 1830.
