We made lots of stops along the way on our visit to Istanbul, and one of the favorites was Hagia Sophia.
Built by the Byzantine Emporer in 537 and used as the Great Church in Byzantine for 916 years, this place is quite unique. It was made into the mosque later and known as the Great Mosque in the world of Islam for 481 years. It was eventually opened as a museum in 1935.
The Islamic calligraphic roundels suspended from the main dome since the 19th century remain in place and make for a fascinating religious contrast with the uncovered Christian mosaics.