A unique Romanesque church built in the 11th century, probably in honor of Matilda of Canossa. It is located below street level, perhaps symbolizing the stages of the city’s development.

The building is round, unlike most churches in Italy, and some say its shape is a tribute to the Church of the Holy Sepulchre in Jerusalem.

The interior is notable for its supporting columns, the women’s choir, and several surviving frescoes.