JESI, a city in the circle and province of Ancona, Italy, is situated on a slight eminence on the left bank of the Esino, 17 miles west-south-west of Ancona, with which it is connected by rail. It is surrounded by a wall with towers. Ths streets, of which the Corso is the finest, are fairly good, and contain several noteworthy buildings, including a theatre and several churches. The cathedral, restored in the 18th century, is dedicated to St Septimius the martyr, who was first bishop of the see in 308. Jesi possesses a hospital and several benevolent institutions, besides a seminary, a lyceum, a communal college, and other educational establishments. It is one of the most active industrial towns of the province. Its manufactures include silk and woollen stockings, paper, cordage, leather, &c. ; and it carries on trade in wine, oil, and grain. Jesi takes its title of " royal " city from having been the birthplace of the emperor Frederick II. in 1194. The populatime is 11,469.

Jesi represents the Roman colony and inunicipium .,'Esis (in Strabo, yEsium), which traces a traditional origin to the l'elasgi. Vestiges of Roman remains render improbable the opinion that, after being destroyed during the barbarian invasion of Italy, the town was removed to a new site. Jesi was a bone of contention between the Longobardi and the Byzantine exarchs, who alternately possessed it. Ultimately it fell into the hands of the Franks. During the early Middle Ages it enjoyed prosperity under Frederick I1. and his immediate successors; but about the beginning of the 14th century it began to have its full share of internal and external troubles. It passed into the power of the Holy See in the pontificate of Nicholas V. (1447-1455) ; under Napoleon it figured as a vice-p•electure; and in 1H0 it w as incorporated with the kingdom of Italy.