At 840 feet ( 260 m ) it was the second - longest aqueduct on the Erie Canal system .
The stone Seneca River Aqueduct ( Richmond Aqueduct ) , which carried the canal over the Seneca and Clyde Rivers , opened in 1857 after eight years of construction .
At 840 feet ( 260 m ) Seneca River Aqueduct was the second - longest aqueduct on the Erie Canal system .
The stone Seneca River Aqueduct ( Richmond Aqueduct ) , which carried the canal over the Seneca and Clyde Rivers , opened in 1857 after eight years of construction .