A feat of Roman engineering that was unsurpassed for more than 1,000 years has been unearthed beneath London.
Archaeologists have discovered two "outstanding" water wheels, powered by a treadmill and capable of bringing 60,000 gallons of water to the surface each day. The bucket-chains are the most complete and best preserved Roman water lifting machinery ever found and may have supplied London's public buildings, bath houses or factories.
Experts believe the wheels are so sophisticated that Britain's first industrial revolution can be said to have taken place in the first century.
The machinery was discovered in two infilled wells in Gresham Street in the City earlier this summer. The site was at the heart of Roman London, close to its amphitheatre and near a bath house.
Tree-ring dating has shown that the earliest well and wheel was built around 63AD, shortly after Boudica's rebellion left much of the city in ruin. The 20 ft. well may have been part of its rebuilding.
Water was drawn using around two dozen boxes, carved from oak and each able to hold three pints. They were fixed together in a loop using wooden and metal pins.
Although nothing remains of the lifting mechanism, contemporary accounts suggest that a treadmill powered by a slave would have hauled the chain. The well was used for about 10 years but collapsed and was filled in by 71AD.
The second wheel was built around 109AD and was used for several decades until it was destroyed by fire. Its chain was far more sophisticated and was made from links of wrought iron, many of which are still intact.
Many homes in London would have had their own private wells. The newly discovered "industrial" wells would have been used for large, public buildings such as bathhouses or for leather, glass or pottery factories. They might even have been part of a network of drinking water for the city.
Nick Bateman, who led the excavation project for the Museum of London's archaeology service, said that there was probably a whole group of these wells.
"Nobody has ever discovered anything like this in Britain," he said. "This is of the quality of Medieval Europe or even the Industrial Revolution.
"We speculate that the people involved in the design and building were the Roman military. It implies a knowledge of engineering and hydraulics which was pretty sophisticated and probably came from people who had come into Roman Britain."
The remains, which include intact wooden buckets, metal links and oak planks used to line the well, are now on display at the Museum of London. A full size reconstruction of the bucket-chains will be completed next year.