It was principally the widespread introduction of a single feature, the pointed arch, which was to bring about the change that separates Gothic from Romanesque. The technological change permitted a stylistic change which broke the tradition of massive masonry and solid walls penetrated by small openings, replacing it with a style where light appears to triumph over substance. With its use came the development of many other architectural devices, previously put to the test in scattered buildings and then called into service to meet the structural, aesthetic and ideological needs of the new style. These include the flying buttresses, pinnacles and traceried windows which typify Gothic ecclesiastical architecture. But while pointed arch is so strongly associated with the Gothic style, it was first used in Western architecture in buildings that were in other ways clearly Romanesque, notably Durham Cathedral in the north of England, Monreale Cathedral and Cathedral of Cefalù in Sicily, Autun Cathedral in France.
What is the name of the cathedral in Sicily that first displayed the use of the pointed arch? (If the question is unanswerable, say "unanswerable")
Cathedral of Cefalù