%substruction%

n. [ L. substructio, fr. substruere, substructum, to build beneath; sub under + struere to build. ] (Arch.) Underbuilding; the foundation, or any preliminary structure intended to raise the lower floor or basement of a building above the natural level of the ground. [ 1913 Webster ]

It is a magnificent strong building, with a substruction very remarkable. Evelyn. [ 1913 Webster ]