The area takes its name from the church of S. Agnes, apparently built before the year 1000 by the family Melini.
The story of St. Agnes, which resembles very much that of Saint Lucia, dates back to the Roman Empire: Angese was martyred very young (apparently about 12 or 13 years) and highly venerated by the Christian community.
There are various versions of her martyrdom: by being burned alive, to being beheaded since the fire did not tuch her, up to being first put in a brothel where only one young man had the courage to try to approach her being blinded by an angel.
Over the centuries many curious episodes have occurred in the St. Agnes. We name a few: in the district were transported in the fourteenth century the inhabitants of the island of Poveglia, quarrelsome and disobedient to the government. At St. Agnes began the plague of 1600, brought by Giovanni Maria Tirinello, carpenter, who lived behind the tower and that seems to have contracted the disease by going to work for the Guardians of Health on the San Clemente island, where the Marquis of Strigis , ambassador of the Duke of Mantua, had recently died of the plague with five servants. An explosion generated by the excavation for the construction of an artesian well, resulting in a column of mud and sand, driven by the water and gases emitted during the drilling, to come up to forty meters high then falling upon the church and the adjacent buildings.
At the center of the square is a well head, dating from 1500, which shows the date of construction and a relief which, it is said, depicts St. Agnes with the palm of martyrdom and a lamb.