Vernio is a comune in the Province of Prato in the Italian region Tuscany, located about 30 kilometres northwest of Florence and about 20 kilo…Vernio is a comune in the Province of Prato in the Italian region Tuscany, located about 30 kilometres northwest of Florence and about 20 kilometres north of Prato. Vernio's name derives from that of an ancient Roman winter camp located here. A Roman bridge existed in the area, but was destroyed during World War II.