Excavations have revealed a 190ft-long stretch of fortifications which once bristled with sharpened stakes on which the Londoners hoped the attacking Vikings would impale themselves.
Before the Viking attacks, most of London's 3,000-5,000 people lived in what is now the West End of the capital - not too many traffic jams then. Indeed, Londoners probably did not realise they were trying to protect themselves against a race which worshipped a version of Santa Claus - Odin used to fly on horseback distributing presents to children.
But the archaeological evidence suggests London's Anglo-Saxon defenders were more worried that the Vikings would engage in raping and pillaging. They built a rampart, probably complete with wooden palisade, and dug a 17ft-wide 7ft-deep V-shaped ditch, the inner face of which was arrayed with lethal wooden stakes.
The Covent Garden discoveries suggest that at the time of the first Viking assault, Anglo-Saxon London, known as Lundenwic, was defended by up to two-thirds of a mile of defences. The first Viking attack occurred in AD842 and the Anglo-Saxon Chronicle says there was a "great slaughter" in London. It seems the defences being unearthed by the archaeologists were not strong enough to hold back the invaders.
Evidence from the excavations reveals at least part of Lundenwic was abandoned at this time. Evidence of occupation in the Covent Garden area appears to cease in the 840s. And archaeologists have found several burned buildings, some of which may have been destroyed during the attack.
Viking raids continued in the London and Home Counties area for decades, and the insecurity caused some wealthier Londoners to hide their money, by burying it in the ground.
Just such a cache, the fourth central-London coin hoard known from this period, has been unearthed in the Covent Garden excavation.
Unusually, it consisted of 23 silver alloy coins minted in the kingdom of Northumbria in the 840s, and it probably belonged to an Anglo-Saxon merchant who hid it in the 850s or 860s and presumably perished before he could retrieve it.
The Covent Garden excavation, led by the Museum of London archaeologists Gordon Malcolm, David Bowsher and Bob Cowie, is also yielding an unprecedented quantity of information about early Anglo-Saxon London.
About 2,500 square metres of Anglo-Saxon Lundenwic have now been excavated at the Opera House site, an archaeological investigation which has produced 3,000 pottery shards, 100,000 pieces of animal bone and 800 bone, antler, glass and other artefacts.
For the first time, archaeologists have been able to see how early Anglo- Saxon London was laid out. The excavations suggest Lundenwic was laid out on a grid system, with well- maintained, gravelled, 3-to-4 metre wide north-south streets apparently connected by equally wide, though less well- maintained, east-west streets.Reuse content