Three underground vaults exposed next to and north of the synagogue at Moza were part of a subterranean water reservoir of a Crusader-period building that existed at the site. Two of the ashlar-built vaults are parallel, with pointed ceilings treated with dark gray plaster. The vaults were separated by three arches borne by square pillars, constructed from ashlars bearing the typical Crusader diagonal dressing and mason’s marks. Apparently, water was conveyed to the vaults via a channel from nearby springs. The third vault incorporated a chute that drained the water into it. Above the underground water reservoir were a Crusader hall and courtyard. This building was probably part of the extensively developed array of settlements, farms and roads, which were constructed in the region between the twelfth century and the end of Frankish rule in 1187 CE.