 About 230 Roman amphitheatres have been found across the area of the Roman Empire.Their typical shape, functions and name distinguish them from Roman theatres, which are more or less semicircular in shape; from the circuses (similar to hippodromes) whose much longer circuits were designed mainly for horse or chariot racing events; and from the smaller stadia, which were primarily designed for athletics and footraces.The earliest Roman amphitheatres date from the middle of the first century BCE, but most were built under Imperial rule, from the Augustan period (27 BCE–14 CE) onwards.