Villa Mondragone

Villa Mondragone is a patrician villa originally in the territory of the Italian comune of Frascati (Latium, central Italy), now in the territory of Monte Porzio Catone (Alban Hills). It lies on a hill 416m above sea-level, in an area called, from its many castles and villas, Castelli Romani about 20 km (12 mi) southeast of Rome, near the ancient town of Tusculum.

Construction began in 1573 by Cardinal Mark Sittich von Hohenems Altemps, who commissioned the design for it and for the Palazzo Altemps in central Rome from Martino Longhi the Elder, on the site of the remains of a Roman villa of the consular family of the Quinctilii.

Pope Gregory XIII, whose heraldic dragon led to calling the villa "Mondragone", used the villa regularly as a summer residence, as guest of Cardinal Altemps. It was at the Villa Mondragone that in 1582, Gregory promulgated the document (the papal bull "Inter gravissimas") which initiated the reform of the calendar now in use and known as the Gregorian calendar.