Evidence of a prehistoric causeway has been uncovered during flood defence work on the marshes of Suffolk.
The timber posts have been preserved by the wet conditions
Contractors working on the Environment Agency's excavation of a new dyke on Beccles town marshes found timber remains which had been hand-sculpted.
Archaeologists said the wooden causeway was used from the Bronze Age in about 1000BC, through the Iron Age to Roman times and the 4th century AD.
The site will now be analysed and dated with the results published this year.
Archaeologists from the University of Birmingham and Suffolk County Council Archaeological Field Services Team were called in to investigate the find.
Results suggest the more than 2,624ft (800m) long wooden causeway may have run from dry land on the edge of Beccles, across a swamp to a spot on the River Waveney.
A 98ft-long (30m) section of the causeway has been recorded with more than 40 in-situ timber posts uncovered.
The 16ft-wide (5m) causeway would have carried carts and was the Bronze Age equivalent of a motorway.
The wet conditions of the site mean that organic material such as wood has been well preserved.
A 98ft-long (30m) section of the causeway has been recorded
Jane Sidell, from English Heritage, said: "This is the first such structure to have been discovered within Suffolk, and is one of only a few in Britain, and as such is a nationally important find.
"It gives us an excellent opportunity to examine ancient, possibly ritual, use of the marshland, and how the marshes have developed over time."
Dr Henry Chapman, from the University of Birmingham, said: "You have got a causeway which has been used for a tremendous amount of time, which is unique - we haven't got something like that.
"It has been added to over time to preserve it, which shows its importance to early Beccles."