The little Hagia Sophia Mosque at the first was a church but later turned into a mosque. At the beginning, in the Byzantine Era it was constructed by the order of Justinian I (the Emperor of Byzantine) and his wife in order to be used as a church for the sake of Monophysite Community in sometime between 527-536, just before Justinian built Hagia Sophia. Named after Sergius and Bacchus (the two main saints of Christians in the Roman army), it has been known as Little Hagia Sophia.
Little Hagia Sophia is taken placed 30×34 square meter. And Its dome which 19 meters high is located over the arch with eight-footed. Also that fascinating building’s dome is architecturally magnifical and its plan – an irregular octagon – is absolutely unusual, its interior section was originally ornamented with gold mosaics and featured columns made from fine green and red marble like Hagia Sophia. The mosaics are worn out, but the impressive columns remain. The church was turned into a mosque by the Hüseyin Aga (chief white eunuch ) around 1500; his tomb is stayed forecourt of the mosque.