Rather than tolling the death knell for Roman London, Boudica's revolt in 60 AD kick-started its golden age. Recognising the strategic military and commercial importance of the town, Emperor Nero appointed a procurator (or civilian administrator) to work alongside the military governor in re-establishing peace. The fire-ravaged settlement was then rebuilt in grand style as a properly planned Roman town.
The expansion was rapid and by the middle of the 2nd century, Londinium had replaced Colchester as capital of Britannia. There was development both north and south of the river, but the heart of the town was in the area we now call the City of London. Public life centred on a large forum – a combined marketplace, administrative hub and law court. The basilica – or town hall – at its centre was the largest west of the Alps. In fact, it was larger than St Paul's cathedral. The centre line of the old forum is marked by present-day Gracechurch St.
Londinium also boasted a palace, a temple, bathhouses, an amphitheatre and a large fort. Building works over the last century have given archaeologists an opportunity to investigate many of these public buildings. The palace, for instance, an elaborate building with grand reception rooms and offices, lies beneath Cannon St station. It may well have been the procurator's residence. The amphitheatre was discovered unexpectedly beneath the Guildhall. The fort, home of the city garrison, lies beneath the Barbican, while the remains of a temple to Mithras are near Wallbrook.
Development of the town had probably peaked by the time Emperor Hadrian visited Londinium in 122 AD. With a population of around 45,000 from all corners of the Empire, London was, even then, a cultural melting pot.
But by the 3rd century, Londinium's star was on the wane, due to tightening recession and political instability across the Empire. A dwindling population could no longer support the cost of elaborate building projects and whole areas of the city were even pulled down. Barbarian incursions and pirate attacks were also becoming more common so, in about 200 AD, the Romans built a defensive wall around the city.
The settlement continued to shrink over the next two hundred years. In the early 4th century, London's major public buildings were systematically demolished – perhaps as punishment for a rebellion against Roman rule – and the entire settlement south of the river was abandoned. The only building work of any significance was on the defences.
Over the next hundred years, soldiers were repeatedly siphoned away from Britannia to deal with barbarian invasions elsewhere. In 407 AD, Emperor Constantine II recalled the last of the troops. Three years later, Emperor Honorius refused one final request from the British for military aid. It was the official end of Roman rule – and the beginning of the end for Roman London. By the mid 5th century, Londinium has been completely abandoned.