No injuries were reported.
The church was closed to the public at the time and is normally open only for marriage ceremonies, but dogs were brought in to sniff through the rubble to make certain no one had been buried, the fire department said.
The roof collapsed onto the floor of St Joseph the Carpenter, which was built in the 1500s on top of the ancient Mamertine prison, where the defeated Gallic king Vercingetorix and Saints Peter and Paul are said to have been held.
Wooden beams and terracotta tiles were scattered in piles across the floor of the church, and one beam crashed through the floor and vaulted ceiling of a chapel below, fire official Luigi Liolli said shortly after inspecting the damage.
Italy has sought to attract private investors to renovate its historical sites, including the Colosseum, as budget austerity has cut into spending needed to maintain the country’s rich historical and artistic heritage.
In recent years several walls have collapsed in the ancient city of Pompeii, which was buried in volcanic ash almost 2,000 years ago.
Pompeii, which has been partially excavated by archaeologists, is one of Italy’s most popular tourist attractions.
