A 52-year-old tourist from Spain has been killed by falling masonry in one of Florence’s most famous churches, the Basilica di Santa Croce.

The fatal accident at the church where Michelangelo, Galileo Galilei and Niccolo Machiavelli are buried raised questions about the state of Italy’s many ageing and fragile monuments.

The country’s culture minister, Dario Franceschini, speaking from New York, said prosecutors would conduct an investigation to determine whether faulty maintenance was to blame.

The victim was struck by a piece of decorative stone that fell from a height of 20 metres (66ft) as he visited the church with his wife. According to Italian media reports, the fragment was about 15cm x 15cm (6in x 6in).

The 15th-century basilica, which has a famed neo-gothic facade, has been undergoing years of maintenance in collaboration with Italy’s civil protection agency, Irena Sanesi, the head of the organisation that manages the church, told the Italian news agency Ansa.

“We are really astonished at what has happened, and we ask ourselves how it could happen,” she said.

Authorities were checking the stability of the church, which is expected to remain closed to visitors indefinitely.

Other deadly incidents involving Italian monuments include the 1989 collapse of a 14th-century bell tower in the northern city of Pavia, in which four people died. The cause of the accident has never been determined.

A toddler and a 30-year-old were seriously injured in July when plaster fell from the ceiling of the Acireale Cathedral in Sicily during a wedding.

In October 2012, a cornice fell from the wall of the royal palace of Casertanear Naples causing part of the roof to cave in just a few feet from tourists. No one was injured.