Plan of St. Sernin, Toulouse
"It was in Central France, and mainly along the Loire, that the systematic development of vaulted church architecture began. Naves covered with barrel-vaults, sometimes of pointed section, appear in a number of large churches built during the eleventh and twelfth centuries, with apsidal and transeptal chapels and aisles carried around the apse, as in the imposing church of St. Sernin at Toulouse, in Provence. The thrust of these ponderous vaults was clumsily resisted by half-barrel vaults over the side aisles, transmitting the strain to massive side-walls."
A. D. F. Hamlin College Histories of Art History of Architecture (New York, NY: Longmans, Green, and Co., 1915)