Turkey is a nation straddling Eastern Europe and western Asia with cultural connections to ancient Greek, Persian, Roman, Byzantine and Ottoman empires. Cosmopolitan Istanbul, on the Bosphorus Strait, is home to the iconic Hagia Sophia, with its soaring dome and Christian mosaics, the massive 17th-century Blue Mosque and the circa-1460 Topkapı Palace, former home of sultans. Ankara is Turkey’s modern capital. The area of Turkey has been inhabited since the Paleolithic period. After Alexander the Great's conquest, the area was Hellenized, a process which continued under the Roman Empire and its transition into the Byzantine Empire. In the mid-14th century the Ottomans started uniting Anatolia and created an empire encompassing much of Southeast Europe, West Asia and North Africa, becoming a major power in Eurasia and Africa during the early modern period. Turkey's current administration headed by president Tayyip Erdoğan has reversed many of the country's earlier reforms which had been in place since the founding of the modern republic of Turkey, such as Freedom of the Press, a Legislative System of Checks and Balances, and a set of standards for secularism in government, as first enacted by Atatürk. Tourism in Turkey has experienced rapid growth in the last twenty years, and constitutes an important part of the economy. The Turkish Ministry of Culture and Tourism currently promotes Turkish tourism under the Turkey Home name. Turkey has 13 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"; and 51 World Heritage Sites in tentative list, such as the archaeological sites or historic urban centres of Göbekli Tepe, Gordion, Ephesus, Aphrodisias, Perga, Lycia, Sagalassos, Aizanoi, Zeugma, Ani, Harran, Mardin, Konya and Alanya. Turkey hosts two of the Seven Wonders of the Ancient World: the Mausoleum in Halicarnassus and the Temple of Artemis in Ephesus.