The origins of the territory of nowadays Fiano Romano goes back to VIII-IV BC.
The first official mention appears in a document dated from 9th century, in which the FUNDUS FIANUS is mentioned among the properties of the Abbey of Farfa. The toponym, first documented as FIANUS in 1268, is a probable formation of the Latin name FILLIUS or OFFILUS with the adjectival suffix -ANUS, which indicates land tenure. Its position on the Tiber river made it a fluvial port of some importance throughout the Middle Ages.
Its fortress passed in the 11th century to the monks of San Paolo, who in the 14th century ceded it to the Orsini family. In the following centuries it knew various alternations of power: from the Sforza to the Ludovisi, from the Ottoboni to the Menotti, who came into possession in 1897.
The historic town centre is accessed through the monumental Porta Capena, built with stone blocks and adjoining the fifteenth-century ducal castle. The latter, which houses antique furnishings and coats of arms along with valuable frescoes, is made up of a powerful central cylindrical keep flanked by a square tower and fortified with straight walls crowned by Guelph battlements.
The church of Santo Stefano Nuovo, divided into three naves, is embellished with thirteenth-century frescoes and sepulchral monuments while the church of Santa Maria ad Pontem, dating from the 10th century, has been restored to its original look.