The dome is divided into eight sectors, meeting at the lantern oculus. Each side of the entablature has a lunette, and in the angles between these are oval tondi from which the molded ribs spring. Sectors, lunettes (except one) and tondi are all frescoed, the theme of the dome being The Assumption of Our Lady. She is in one of the sectors, the rest being occupied by angels. The lunettes show scenes from the Life of St James the Great. The work is by Pietro Paolo Naldini.