Famed for its architecture, the Hagia Sophia in Istanbul stands as an icon and represents the city's history. For these reasons it draws thousands of visitors every year. After serving as both a church and mosque, Hagia Sophia makes for a fascinating visit if you appreciate religious art and architecture as well as its famed dome, which can be seen across the city and is instantly recognizable. It is not just a national monument but it is acknowledged as one of the world's greatest structures. Testament to this is its UNESCO World Heritage status given to protect this site and other historic monuments in the city, gained in 1985.