Built 1731

Mission Espada Aqueduct (Bexar County, Texas)
Built between 1731 and 1745
Stone arch bridge over Piedras Creek on Acequia Madre
Still carries water

Old Stone Bridge (Somerset County, New Jersey)
Planned in 1683, built 1731, site of 1777 Battle of Bound Brook; creek later filled in and bridge buried intact
Stone arch bridge over Unnamed creek on Olde York Road
Filled in