It is open to visit from Tuesday to Sunday between 09am and 7:30pm. Upper gallery closes at 7pm. It is a former Byzantine church and former Ottoman mosque and today museum in Istanbul. It has always been the precious of its time and today it is a perfect synthesis where one can observe both Ottoman and Byzantium effects under one great dome. Hagia Sophia’s influence, both architecturally and liturgically, was widespread and enduring in the Eastern Orthodox, Roman Catholic, and Muslim worlds alike. It is definitely one of the best in Istanbul.