The huge dome of the church is 32 inches wide. 5 meters, 56 meters high, became the prototype of Byzantine architecture later. Justinian I chose isidore, a physicist, and Ansimius, a mathematician from Terrace, as architects to rebuild the cathedral, among whom Ansimius died before the church was built. This huge building took only five years to complete, and its dome created a huge worship space, supported by four sail arches towering above the arch. This is the first dome built with this suspension structure in the world. There are 40 high side windows around the wall to let the light shine in, while the passages around the building are covered with colonnades. Later, two semi-domes with the same diameter as the main dome were added as buttresses of the main dome. /kloc-in the 6th century, a brick steeple was added to the building.