"The City is a compact site which has been built and lived upon for upwards of 2,000 years of intensive use and crowded history."
Proposals for Post War Reconstruction in the City of London”, Corporation of London, 1944
The history of the City began with the Roman invasion of Britain in 43 AD. The Romans built a town thirty acres in size on modern Ludgate Hill and Cornhill and called it Londinium. Ten years later the town was burnt and looted by Boadicea, queen of the Iceni, a tribe from East Anglia. Roman rule was quickly re-established and Londinium was rebuilt on a much larger scale. The Romans used to prefabricate frames for walls and floors and reassemble them on site, where they were finally plastered and roofed for use. So rebuilding was swift. Civic buildings were built of stone and marble and were on a grand scale. By AD 100 Londinium was the capital of the province of Britannia. Eventually it covered three hundred acres, making Londinium one of the largest cities in the Roman West.
During the rebuilding period, the Romans built a fort at the north-west boundary of Londinium. It had gates in each of the four walls, and it was the gate in the north wall which in later times became known as the Cripplegate, and gave this name to the whole area. In the 3rd century AD, the Romans built a wall round Londinium to protect it from the new threat of attack by Anglo Saxon sea raiders. The wall incorporated two of the existing walls of the fort and its towers. Some of the wall is still visible today along London Wall and in St Alphage Garden. (St Alfege was the first English martyr, beaten to death by Vikings for refusing to allow himself to be ransomed). Aldersgate Street takes its name from another of the now-vanished gates in the wall.
The land on which the Barbican Estate is built was outside the Roman City walls. In Roman times, the ground was twenty feet lower than today and it was marshland into which water from the town drained. In bad weather it became a lake dotted with islands.
In 410, the Emperor Honorius withdrew the legions from Britain to prop up the disintegrating Eastern borders of the Empire, and Roman rule effectively ended. Over the next few hundred years, the Romanised Britons were gradually displaced by Anglo Saxon invaders. The invaders were farmers not merchants and the Roman town became largely abandoned.