sentences:  Many of the Romanesque cathedrals were modernised with Gothic elements.Thus, the Romanesque nave of Oporto Cathedral is supported by flying buttresses, one of the first built in Portugal (early 13th century).The apse of Lisbon Cathedral was totally remodelled in the first half of the 14th century, when it gained a Gothic ambulatory illuminated by a clerestory (high row of windows on the upper storey).