In ancient and medieval times the whole city was surrounded by walls and was entered through about ten gates. The walls had become old and unnecessary so they were pulled down at the beginning of the 19th century. Parts of the walls between the Twin Gates and the Giardini square have been preserved until today.

The Twin Gates, thus called because of the two arches through which you enter the inner yard, which was once the entrance to the city, were constructed between the 2nd and 3rd centuries. The Twin Gates today lead to the Archaeological Museum and the Castle. Remains, partly restored, of an octagonal sepulchral structure - Mausoleum from the 1st - 2nd centuries have been found opposite the Twin Gates.