Two perpendiculary placed intersecting barrel vaults form a groined vault.

The central hall of the market of Trajanus (early 2nd century - Rome) is roofed by a serie of groined vaults. The long central barrel vault is intersected by several perpendiculary placed barrel vaults. This solution is a better solution than one simple barrel vault.[br][list][*]as a construction: the perpendiculary placed barrel vaults neutralize each others horizontal forces.[/*][*]as a spacial result: the hall becomes higher and larger. The perpendiculary placed barrel vaults allow better natural illumination of the hall providing it a much more open character.[/*][/list]

The baths of Caracalla (early 3th century - Rome) had place for thousands of bathing guests. The construction reaches a span of 30 m, using groined vaults.