Geography and demography of the roman empire
The Roman Empire was one of the largest empires in history, with large territories around Europe, North Africa and Middle East. Neither time nor space limited the Empire at its greatest extent. In the Aeneid, limitless empire is said to be granted to the Romans by their supreme god Jupiter. This universal dominion was renewed and bolstered when the Empire came under Christian rule in the 4th century. By and large, Rome's expansion was mostly succeeded by the Republic, though parts of Northern Europe, including Breton, came under Roman control in the 1st century AD. During the reign of Augustus, a global map of the known world was displayed for the first time in public and this map survives from antiquity by the Greek writer Strabo. One of Augustus's achievements was that peoples and places within the Empire were geographically catalogued. The Empire reached its largest expanse under the emperor Trajan (98-117 AD), and covered an area of five million square kilometres. Each of the three largest cities of the Empire - Rome, Alexandria and Antioch - was almost double the size of any European city at the start of the seventeenth century. Trajan's successor Hadrian created the policy of maintaining the Empire rather than expanding it. Borders were marked and frontiers were controlled by the army and this was the time when Hadrian's Wall was built dividing Breton from the Picts in Britain. But the most heavily fortified borders were the ones that were unstable. Hadrian's Wall is an example of these frontiers.