Tourism in Turkey has increased in almost every year in the 21st Century. Turkey has 17 UNESCO World Heritage Sites, such as the Historic Areas of Istanbul, the Rock Sites of Cappadocia, the Neolithic Site of Çatalhöyük, Hattusa: the Hittite Capital, the Archaeological Site of Troy, Pergamon and its Multi-Layered Cultural Landscape, Hierapolis – Pamukkale, and Mount Nemrut.