The need for settlements to withstand attacks led to the construction of many impressive defensive structures. The formidable twin walls of Babylon were an early example. A wonder of the ancient world, its multi-layered defences were built from baked brick and reinforced by a surrounding moat. Greek historian Diodorus stated that the construction took 200,000 men a full year to complete. On standing before them, Cyrus the Great, commander of the besieging Medo-Persian forces exclaimed “I am unable to see how any enemy can take walls of such strength and height by assault”.
