Built by Justinian as the Church of Sergius and Bacchus (patron saints of the Roman army), this church is commonly known as the "Little Aya Sofya" due to its resemblance to the great church up the hill. In fact, it was built just before Aya Sofya, in the 530s, and the architects explored here many of the same ideas of the larger church but on a smaller scale. The church was converted to a mosque around the year 1500 by Hüseyin Ağa, Beyazıt II's chief eunuch. Though
the mosaics are long gone, a Greek inscription dedicated to Justinian, his wife Theodora, and the saints can still be seen running along the cornice of the colonnade. The marble and verd antique columns with their delicate, ornate capitals are also quite impressive, and you can climb the stairway to the upper-level gallery for a closer look.
Küçük Aya Sofya Cad., Istanbul, Turkey