The final stone was laid in 1593 by Jules Guistiniani, made bishop by Pope Sixtus V.[1] It is where Napoleon Bonaparte was baptised on 21 July 1771[2] and he recited the following on his deathbed in Saint Helena in 1821: "If they forbid my corpse, as they have forbidden my body, deny me a small piece of land in which to be buried, I wish to be buried with my ancestors in Ajaccio Cathedral in Corsica.

According to legend, on 15 August 1769 which was also the feast of the Assumption, Letizia Buonaparte felt sudden and severe labour pains while in the cathedral for mass.

The building also has two aisles that depart from the front door and go up to the transept, separated in the middle by the seven chapels beside two rows of three columns.

It is a simple bowl engraved with Giustiniani's coat of arms, surmounted by a Tuscan bronze crown, below which there is a gold inscription, Heic baptisatus Magnus Imperator (Latin for Here is baptised the Great Emperor).

The altar is in polychrome marble, and it was originally located at the Church of the Suffragio in Lucca but was given to the cathedral by Elisa Bonaparte, Napoleon's sister in 1809.