Turkey has many historical sites and natural wonders that are popular tourist destinations. Some of the most notable sites in Istanbul include Topkapi Palace, the Blue Mosque known for its blue tiles, Hagia Sophia which has served as both a church and mosque, and historic towers like the Maiden's Tower overlooking the Bosphorus Strait. Other major attractions outside Istanbul include the ancient Greco-Roman city of Ephesus, the unique fairy chimney rock formations and caves of Cappadocia, the mountainside statues of Mount Nemrut, the mineral-encrusted terraces of Pamukkale, the legendary site of Troy, and the ancient city of Zeugma along the Eup