Museo Galileo
Virtual Museum
Gregory XIII (Ugo Boncompagni)
Gregory XIII (Ugo Boncompagni)

Pope from 1572 to 1585, Gregory XIII was a staunch advocate of the Catholic Counter-Reformation initiated by the Council of Trent (1545-1563). He sponsored the development of the Roman College of the Jesuits. He is particularly remembered for overseeing the reform of the Julian calendar (1582), which was replaced by the "Gregorian" calendar.