Lombardy is one of the twenty administrative regions of Italy. It has an extent of 23,844 km2 (9,206 sq mi) in the northern-central part of the country, and a population of about 10 million people, constituting more than one-sixth of the population of Italy. Over a fifth of the Italian gross domestic product is produced in the region. The metropolitan area of Milan is the largest in the country, and is among the largest in the European Union. Of the fifty-eight UNESCO World Heritage Sites in Italy, ten are in Lombardy. Virgil, Pliny the Elder, Ambrose, Caravaggio, Claudio Monteverdi, Antonio Stradivari, Cesare Beccaria, Alessandro Volta, Alessandro Manzoni, and popes John XXIII and Paul VI are among those with origins in the area now known as Lombardy.