In the 1970s, this is what was left of the aqueduct which carried the Lehigh Canal over the Aquashicola Creek. The Central of New Jersey trestle is visible in the background.
This was the lock below where the Aquashicola creek emptied into the Lehigh River. The canal itself did not run through the gap; it was open water for canal boats. For more information, see http://www.loc.gov/pictures/item/pa1877/