It is a town in the province of Varese, situated in the plains of Lombardy, a few km from Saronno. It probably has Roman origins: the name "Gerenzanum" as the best hypothesis derives from the combination of the words "glares" (gravel) and "ager" (field). After the fall of the Roman Empire it subdued the barbarian invasions first, and the Lombard invasions later. The village is mentioned for the first time in an official document of 1174 (a deed of the "Curtis di Gerenzano" in which the family Maineri received the rights to rule over the town from the Abbey of Padua of San Pietro in Ciel d'Oro). During the XIV century Gerenzano was under the direct rule of Milan (first with the Visconti and then with the Sforza), whilst in the XVII century the town was ruled by Lords of Fagnani, who became Marquis by permission of King Charles II of Spain. In 1840 the town was ceded to the Clerici, with whom it became part of the Kingdom of Italy.

Among the sites of interest, worth of mention and not to miss:
- the XIII century Church of Saints Peter and Paul;
- the Church of St. James, built in 1512 on an existing structure XIV century;
- the fountain of St. James;
- the Park of the Herons.