Version 3 - the current one - was completed 1500 years ago. It is 7,000+ sq meters of floor space (70,000 sq ft) and the ceiling is 59m (180 feet) high. Which makes it bigger and taller and a thousand years older than the great French cathedrals we visited last spring. Here are a couple of photos from inside.
In the late 1400s Constantinople fell to the invading Muslim army and Constantinople became the capitol of the Ottoman empire. Sophia was converted from a church where people had prayed to Mary for the prior 900 years, to a mosque where people would pray to Allah for the next 500. Finally, in the 1920s, it was converted to a museum.
The photos show the image of Mary and the Islamic writings adjacent.