Experts working on the £1.5 billion upgrade of the A14 in Cambridgeshire have uncovered what is believed to be the earliest evidence of beer being brewed in Britain.
Road workers found tiny fragments thought to be part of an iron age brewery while they were carrying out improvements to the stretch of road between Cambridge and Huntingdon.
It's understood that the discovery could date back more than 2,000 years to around the 400BC mark.
Archaeobotanist Lara Gonzalez described the find as "incredibly exciting".
She said that the structures of the charred fragments were similar to bread, but showed evidence of fermentation.
"I knew when I looked at these tiny fragments under the microscope that I had something special," she said.
"The microstructure of these remains had clearly changed through the fermentation process and air bubbles typical of those formed in the boiling and mashing process of brewing.
"It's like looking for a needle in a haystack but it's incredibly exciting to identify remains of this significance and to play a part in uncovering the fascinating history of the Cambridgeshire landscape."
The Ice Age remains of a wooly mammoth, Iron Age settlements and Anglo-Saxon villages have already been unearthed by workers since the A14 upgrade started.
"The work we are doing on the A14 continues to unearth incredible discoveries that are helping to shape our understanding of how life in Cambridgeshire, and beyond, has developed through history," Dr Steve Sherlock from Highway England said.
"It's a well-known fact that ancient populations used the beer making process to purify water and create a safe source of hydration, but this is potentially the earliest physical evidence of that process taking place in the UK.
"This is all part of the work we are doing to respect the areas cultural heritage while we deliver our vital upgrade for the A14."