The Mosul architecture employed the elements of architecture in accordance with the nature of the building, the size of its spaces and their bodies, as well as its environmental and social suitability and the nature of its building materials. Among these elements are the vaults that he used in various types of buildings, from residential ones such as the Totenji House and the Ziada House, religious ones such as the Al-Aghawat Mosque and the Al-Zaywani Mosque, and service ones such as caravanserais, markets, and qaysariyat. These vaults were employed in the roofing of building spaces with rectangular projections instead of flat ceilings, because flat ceilings are completely subject to gravity. As a result, the building in which it is erected fell more than the vaulted ceilings, which are the opposite of the flat ceilings, which prolongs the life of the buildings erected in it as in the halls and rooms, due to its structural durability and climatic treatments, as well as adding prestige and beauty to the building. One of the ways used it in roofing spaces with longitudinal extensions, such as archways, vestibules, Iwans, and basements, as it is supported by a series of successive arches that may range from three to five arches, depending on the length of the spaces, either its vertical sections are in the form of a semicircular arch or in the form of a pointed arch.