London was born almost 2,000 years ago, when the Romans set up a trading post on the banks of the River Thames in 47 AD. They called it Londinium, and the wall that they built around their town corresponds roughly with the boundary of the City of London today. It borders Westminster to the west, Tower Hamlets to the east, Camden, Islington and Hackney to the north, and the River Thames to the south.
The area covers just one square mile and has a population of less than 8,000, far fewer than any other borough in London. In fact, it’s not even a borough, but a city in its own right and is administered by the City of London Corporation. It may be small in size and population, but it has always been one of the most important and influential areas of the city.
After the Romans left, the Anglo Saxons created their own community just to the west of the wall and the former Roman town became virtually uninhabited. However, the location of old Londinium still had its advantages for trading. The Thames being tidal, meant that boats could come up this far, and yet it was still narrow enough to be bridged.