When work on the Grand Canal begun in 1756 Ardclough's was one of the first sections to be dug. The canal reached Ardclough in 1763, when the 13th lock, a double lock built with Pozzuolona mortar, was opened, following to the ambitious design of the canal's original engineer, Thomas Omer. After Omer's plans proved too expensive a new engineer, John Trail, took over construction of the canal in 1768, the proposed canal capacity was reduced from 170 ton barges to 40 ton barges. Canal records show that “ Lyons or Clonaughles lock” was reduced in size in 1783, but the canal through the thirteenth lock serves as a reminder of Omer's original plan, wide, compared with the width adopted by Trail.