The Church of St Augustine was built in the 14th century on the pre-existing Church of San Salvatore in Muro, near the remains of the city walls and the Roman Theatre. In the 19th century it was deconsecrated and used as a military warehouse. It was returned to worship in 1866 thanks to the work of the Oblate Sisters of the Holy Spirit. It houses the venerated Madonna del Sasso and the body of Blessed Elena Guerra.

The adjoining 15th-century convent has a portico with slightly ogival arches supported by octagonal brick columns.

In December 1943, it became the headquarters of the provincial headquarters of the 86th Legion of the Republican National Guard, headed by Bruno Messori, and its Political Investigation Office.

Among the torturers Camillo Cerboneschi stood out, who was known in the post-war period as 'the beast of the province'. Born in Perugia in 1908, but Milanese by adoption, a veteran of the Montenegrin front, he had been caught on 8 September 1943 in Lucca during a brief convalescence leave. Unable to return to his unit, he made himself available to the local Germanic command, managing to gather around him a small nucleus of ex-squadristas [member of Italian fascist squads] and veterans from the front. This group established the UPI, which was active in the search for ex-prisoners and straggling soldiers and then in anti-partisan repression.

After being identified and apprehended, all those suspected of anti-fascist actions were taken to St. Augustine. They were interrogated, tortured and intimidated, and threatened with retaliation against their families. The torture consisted of forced ingestion of liquids, burns inflicted with a stove, and compression of the private parts. He is remembered by victims such as Captain Fiilippo Rubolotta, lawyer Guido Di Grazia and Professor Aldo Muston, among others.

Through these fierce methods and the investigations conducted via a large network of local informers, the UPI achieved important operational successes, including the capture of Vittorio Monti and Domenico Randazzo, accused of being part of the Resistance movement and shot in Massarosa on 19 April 1944, and the mortal wounding of the partisan Roberto Bartolozzi, who died the following 29 June.

With the approach of the Allies, Cerboneschi and his men moved to Emilia where the group disbanded. In 1948, they were tried by the CAS, but only the militant Erminio Barsotti was convicted (and granted amnesty), while Cerboneschi escaped from prison and Messori expatriated to Spain.

In 1975, a plaque was placed to remember their criminal actions.