Gioacchino La Barbera, a former member of the Cosa Nostra mafia, said fellow gangster Nino Gioè told him about the plan in the early 1990s, Corriere della Sera reported.
“Can you imagine if Italy wakes up and can’t find the Tower of Pisa,” Gioè allegedly said.
Gioè was arrested in 1993 over the murder of anti-mafia magistrates in Sicily and committed suicide in prison, La Repubblica said.
While Pisa’s famous tower still stands, the mafia did carry out a number of other bomb attacks in the early 1990s.
In May 1993 a car bomb went off next to Florence’s Uffizi Gallery, killing five people and injuring 37. The same year car bombs hit two churches in Rome.