Castello di Frascarolo, Medieval castle in Induno Olona, Italy.

Castello di Frascarolo is a castle in Induno Olona featuring an original western tower and a formal Italian garden with terraced levels. The garden displays decorated fountains arranged across its multiple zones.

Documented from 1160, when Archbishop Oberto da Pirovano of Milan used it to defend Varese against the Comaschi, the castle may have earlier Lombard origins controlling access to Valganna and Valceresio. From the 12th century it belonged to the abbey of San Gemolo in Valganna until 1543, when Gian Battista Medici, marquis of Marignano, bought it; two years later Gian Giacomo Medici married Maria Orsini there. The Medici turned it into a 16th-century residence, keeping only the western square tower of its defences.

The Medici turned the fortress into a residence from 1543, when Gian Battista Medici, marquis of Marignano, bought it; two years later the wedding of Gian Giacomo Medici and Maria Orsini was held here. The remodelling drew on the style of Giulio Romano, and the family chapel near the main entrance was reworked in the 17th century. Margherita Medici di Marignano, sister of Pope Pius IV and mother of Saint Charles Borromeo, lived here.

The castle is private and can only be visited with a specific permit; it is about 1 km from the centre of Induno Olona, reached by a road with hairpin bends. The Medici di Marignano family has owned it since 1543 and still does.

Composer Gaetano Donizetti visited in 1837 and left traces of his artistic stay at the location. Later the writer Gian Battista Bazzoni also came here seeking inspiration for his own work.