The top two countries by number of World Heritage Sites are located in this region: Italy with 55 sites and Spain with 48 sites (44 sites not including those on the Canary Islands). Seven sites are shared between several countries: Prehistoric Rock Art Sites in the Côa Valley and Siega Verde (Portugal and Spain), Rhaetian Railway in the Albula / Bernina Landscapes (Italy and Switzerland), Monte San Giorgio (Italy and Switzerland), Historic Centre of Rome, the Properties of the Holy See in that City Enjoying Extraterritorial Rights and San Paolo Fuori le Mura (Holy See and Italy), Pyrénées - Mont Perdu (France and Spain), Prehistoric Pile dwellings around the Alps (Austria, France, Germany, Italy, Slovenia and Switzerland) and Heritage of Mercury - Almadén and Idrija (Slovenia and Spain). The first sites from the region were inscribed in 1979 a year after the list's conception, and included six sites in the former Yugoslavia and one site in Italy. Each year, UNESCO's World Heritage Committee may inscribe new sites on the list, or delist sites that no longer meet the criteria. Selection is based on ten criteria: six for cultural heritage (i-vi) and four for natural heritage (vii-x). Some sites, designated mixed sites, represent both cultural and natural heritage. In Southern Europe, there are 154 cultural, 16 natural, and 5 mixed sites.