Turkey is a state in southeast Europe and southwest Asia, the culture of which combines ancient Greek, Persian, Roman, Byzantine and Ottoman traditions. In multinational Istanbul, stretching along the shores of the Bosphorus, tourists are attracted by the famous Hagia Sophia with its soaring dome and Christian mosaics, the majestic 17th century Blue Mosque and the Topkapi Palace, the former residence of the Ottoman sultans, built in the 1460s. The capital of Turkey is the modern city of Ankara.