answer: Other notable examples are in Cefalù , Cremona , Enna , L'Aquila , Modena , Monreale , Naples , Genoa , Orvieto , Padua , Piazza Armerina , Pisa (the Leaning Tower is the Duomo's bell-tower), Prato , San Gimignano , Siena , Spoleto , Turin and Viterbo .