Castelguglielmo is a comune (municipality) in the Province of Rovigo in the Italian region Veneto, located about 80 km southwest of Venice and about 20 km southwest of Rovigo. As of 31 December 2004, it had a population of 1,730 and an area of 22.1 km2. The municipality of Castelguglielmo contains the frazioni (subdivisions, mainly villages and hamlets) Bressane, Canda, Franceschetta, Le Basse, Precona, and Presciane. Castelguglielmo borders the following municipalities: Bagnolo di Po, Canda, Fiesso Umbertiano, Lendinara, Pincara, San Bellino, Stienta.

Demographic evolution