It had to be the largest church in the world and in the shape of a huge Latin cross, but was only completed the long arm and with the unfinished facade. The basilica is still one of the most beautiful examples of Italian Gothic style and is one of the greatest monuments in the city. The Basilica houses an invaluable number of treasures such as the sundial by Cassini and Guglielmini, which indicates the exact period of the current year at all times, the "S. Rocco" by Parmigianino and the marvelous Bolognini Chapel. From the left nave of the basilica, the visitor can gain access to the Museum where many bas-reliefs are collected.