Scientists have used 70 tons of liquid sugar to preserve the remains of three Medieval bridges found near Leicester.
Experts from the University of Leicester immersed the 11th century bridges – whose ruins were so heavy they had to be carried in sections by eight-man teams – in tanks of sugar solution.
The trio of Medieval bridges were excavated at Heminton Quarry, near Castle Donington in Leicestershire
Leicestershire County Council persuaded British Sugar to provide the sticky haul in three huge delivery batches after a retired local GP found the fragile 11th century timbers in Hemington Quarry in 1993.
"Securing the viability of the bridge is testament to the natural preservative qualities of sugar," said Dr Julian Cooper, head of food science at British Sugar.
"Our long association with the River Trent at Newark made it a privilege to be involved in the restoration of the Hemington Bridge, which once spanned the same river.
"Now we have reached the final stages of this 15 year conservation process, we congratulate the determination of those involved in safeguarding the bridge for generations to come."
The timbers were steam cleaned to remove the sugar solution
The venture is the second time sugar has come to the rescue of curators, echoing a method known as sucrose impregnation which was used by the Waterfront Museum in Dorset to conserve an Iron Age boat found in Poole in 1985.
The bridge sections are thought to have been part of The King's Highway, a major national route linking London and the South with Derby and the North.
They have gone on show at local science hub the Snibston Discovery Museum, where they had been kept in drying chambers for three years in the final part of the project.
A drying chamber at Snibston
"The carpentry and architecture of the 11th century bridge represents a crucial moment in British building history,” said Site Director Susan Ripper.
“It combines the earth-based building technology of Anglo-Saxon England with the timber-frame technology which became commonplace a century later."
Results of an investigation into the bridges' structure and historical context have been revealed in an accompanying book launched alongside the display.
Workmen moved the timbers from the immersion tanks to the drying chamber in the final part of the conservation process
"The timbers are a rare testament to the engineering skills of the early Medieval period and illustrate the importance of the road networks to the economy of the time," said the University's Lynden Cooper.
"They also provide unique evidence of Saxo-Norman woodworking methods."
Ernie White, Leicestershire County Council Cabinet Member for Museums, said the authority was "deeply appreciative" of advice from the sugar company, archaeologists and the University.
"It's amazing to think that timbers from a Norman bridge are being preserved with sugar – and that they could soon be on display to the public," he added.
"We are now looking forward to ensuring that future generations will be able to learn more about this fascinating find."