The Romans created one of the greatest empires in history, built with the help of an incredible army of professional legionnaires and a well-oiled political machinery. At its height, a few hundred men ruled over a fifth of mankind and an area stretching from Britain to Syria and from Gibraltar to the Euphrates. They undertook some of the most ambitious building-projects of their time: endless roads, gigantic bridges and imposing aqueducts formed a complex infrastructure and left a lasting legacy.