Hagia Sophia an Ottoman imperial mosque and now a museum in Istanbul, Turkey. Built in AD 537 in the Late Antiquity, it is famous for its massive dome. It was the world's largest building and an engineering marvel of its time. It is considered the epitome of Byzantine architecture[1] and is said to have "changed the history of architecture"
The Hagia Sophia is of masonry construction. The structure has brick and mortar joints that are 1.5 times the width of the bricks. The mortar joints are composed of a combination of sand and minute ceramic pieces distributed evenly throughout the mortar joints. This combination of sand and ceramic pieces could be considered the contemporaneous equivalent of modern concrete.[3] - source Wikipedia
