Layers of vaults filled the space behind the Temple Mount retaining walls. A paved plaza was laid above the upper story of vaults. Striving to be faithful to Jewish law, Herod insured that the priests officiating in the Temple could not become “impure” by walking over any unmarked graves in the earth below. Jewish law prescribes the construction of vaults, which create voids, over graves as a way of “neutralizing” the power of graves to make those who walk over them ritually impure.