The Walls: In Constantinople, the sacking of Rome in 410 alerted the regent of young Emperor Theodosius II, Anthemius, of the eastern half of the empire, to build a wall to safeguard his city. The wall built with the founding of Constantinople by Constantine in 330 was deemed inadequate. Construction of what became known as the "Wall of Theodosius"; began in the year 413 AD. In 447 an earthquake knocked the wall down. It was rebuilt in three months.
Great City: In the year 800, Constantinople's population was about 250,000 – the greatest city in Europe except perhaps for Cordoba.