As a former church, mosque, and now museum, this structural building represents the crossover that happened to Constantinople from Byzantine rule to Ottoman grandeur. As one of Istanbul’s great glories built between 532 and 537AD, originally by the emperor Justinian, intricate frescoes adorn the ceiling. Representing scenes from the Bible and prominent figures of the Byzantine Empire, they sit next to large circular plagues pinned to the wall that highlight Islamic calligraphy art. The galleries of the upper level are where the best view of the interior of the iconic building is to be seen.