Complex sentence: With the help of funds contributed by Boniface VIII and by many faithful the side aisles were completed in the 1300s, and in 1453 interior construction was finally completed when the main nave was finally covered by its vault.
Split into simpler sentences: With the help of funds contributed by Boniface VIII and the faithful the side aisles were completed in the 1300s. In 1453 interior construction was finally completed when the main nave was covered by its vault.