In Roman times, Porta Pretoria was the main entrance to the city. It was located in the area currently occupied by a branch of the Teresa Ciceri high school.
Porta Pretoria was destroyed at the end of the ten year war against Milan (1118–1127), along with the rest of the city with the exception of its churches. You can see these remains under the courtyard of the high school, during the opening hours of the Paolo Giovio archaeological museum.
Tours are by reservation only. Book your visit by calling +39 031 252 550 from Tuesday to Sunday, according to the following hours: 10 am-12 pm, 3 pm-5 pm.