London, as a settlement, began in the middle of the first century AD when the Roman Emperor Claudius invaded. The settlement grew rapidly during the Roman occupation and it was known as Londinium. Although not important politically, it flourished as a major port due to its ideal location in relation to the river and of course the European continent. All main Roman roads converged on London and mileage and distances were all measured from London radiating outwards, and mostly north into the country.
By the end of the third century Londinium had become the centre of Roman administration and a prosperous walled city with a fort, a large temple, a basilica and a governor’s palace. The fortified city wall around the city can still be traced in fragments – it roughly corresponds with a square mile, which is what the financial centre of London, or the City of London, is known as today – The Square Mile.