The dome was built after the earthquake of 1693.
The structure is a segmental dome, has a single layer, and was once covered with square glazed terracotta tiles, which were removed during the last restoration in 2008. It is punctuated by double ribs converging in the lantern, which has a small crowning dome completed by a metal sphere.
The base of the dome, the tholobate, is cylindrical inside and octagonal outside, and contains eight large windows and a walkway, bordered by an elegant balustrade, which follows its structure.
