The upper orders of the corner towers were built in the 14th-15th centuries while the southern porch was added in the early Renaissance period. The present neoclassical appearance dates from the work carried out in 1781-1801, supervised by Fuga. During this period the great retable by Gagini was destroyed and the sculptures moved to different parts of the basilica. Also by Fuga are the great dome emerging from the main body of the building and the smaller domes covering the aisles' ceilings.