Roman engineering and architecture, such as roads, aqueducts, and the Colosseum, were highly influential and advanced for their time. Roman roads formed the backbone of the empire and linked cities across Italy economically. Aqueducts, considered great engineering feats, supplied water to Roman cities and industrial sites, with some still used today. The Colosseum was a large amphitheater that could seat 50,000 spectators and was originally called the Flavian Amphitheater.