Evidence of a Stone Age settlement has been uncovered by a water company planning to extend a sewage works.
The artefacts will be taken to the West Berkshire Museum
Stone Age flint and Roman items were found at the site in Kintbury, near Hungerford, Berkshire.
The find dates back to 8,000 BC and confirms that a nearby Roman bath site probably had a British owner, a local archaeologist said.
Thames Water is now reviewing its plans to improve the sewage treatment works after realising the site's importance.
The oldest finds date from the Mesolithic period which spanned 10,000 - 4,000 BC.
Pieces of a Bronze Age urn and the remains of three bread ovens, thought to be Roman, were also found at the site.
Duncan Coe, from the West Berkshire Museum, said: "This confirms some evidence found when the original sewage works was built in the late 40s/50s.
"From a time when people were hunter gatherers and the population set up temporary camps and then moved on - it is very significant for the Kennet Valley, for this site.
"It shows continual occupation right through to a Roman village."
Mr Coe added that the bath house might have formed part of the house of a local Briton during the Roman period.
Dr Roy Entwhistle, an archaeologist for Thames Water, said: "Given how quiet this corner of the Kennet Valley is today, it's remarkable to think that so many people have called it home over the last ten thousand years.
"We were particularly pleased to discover the Mesolithic flint work which would have been used by hunter gathers to fashion tools.
"Finding these prehistoric collections undisturbed is rare in Southern England."
All material found on the site of the sewage works will be taken to the West Berkshire Museum.