Considered the finest example of Byzantine architecture in the world, the church of Hagia Sophia was constructed on a scale unprecedented in human history.

Under the rule of Justinian the Emperor, and with a force of 10,000 workers, the dome atop the church of Hagia Sophia was built in record time: it took just five years, ten months, and four days to complete. I chose Hagia Sophia because it is amazing how fast the built such a huge place.

From : Hartransom.org