The Pennsylvania Canal Tunnel was the Pittsburgh terminus of the Pennsylvania Main Line of Public Works, a transportation system that involved other early tunnels. Construction was authorized February 8, 1827, and the tunnel was completed November 10, 1829. The canal crossed the Allegheny River on a covered bridge aqueduct, later replaced by John A. Roebling's first suspension bridge, the Allegheny Aqueduct., the canal traveled underground through most of downtown Pittsburgh, under Grant's Hill, to end in a lock leading to the Monongahela River.