Mesopotamia saw the emergence of the world's first cities like Ur around 4500 years ago, which supported complex societies. Ancient Athens and Rome were not planned cities but organically grew from focal points like the Acropolis and Capitols. The Acropolis became Athens' ceremonial center with temples like the Parthenon, while Rome's forums hosted business and recreation. While Athens grew organically, some ancient towns like Priene were purposefully planned to fit hilltop sites. Many Roman cities and towns were planned as military camps with grid layouts, forums, baths and other buildings in classical styles copied from Greece.