Some of the vast stones are up to two metres in length. © Tyne and Wear Museums.
Excavations at Corbridge in Northumberland have unearthed spectacular discoveries that offer fresh insight into what is thought to have been the largest stone bridge in Roman Britain.
Steadily being eroded by the River Tyne, the remains of the bridge were in urgent need of preservation when Tyne and Wear Museums, backed by English Heritage and a £303,500 grant from the Heritage Lottery Fund, began work earlier this year.
Over the summer, archaeologists, joined by volunteers from the local area and all over the country, unearthed the full length of the bridge’s retaining wall and some of its elaborate decoration.
Experts now believe they have enough information about the bridge to piece together a picture of what an awesome sight it once was.
Describing the recent finds, Margaret Snape of Tyne and Wear Museums told the 24 Hour Museum just how significant the excavation is proving to be.
"It’s really spectacular," she said. "It’s far more than we could have anticipated, not only in the amount of masonry and the state of preservation, but the detail. It’s going to help us work out what the structure of the bridge would have looked like."
Archaeologists were helped by a legion of volunteers both from the local area, across the country and around the world. © Tyne and Wear Museums.
The most completely preserved construction of its type in Britain the bridge was built by the Romans to span the River Tyne.
Lavishly decorated with carved masonry, it once carried the main Roman road from London to Scotland, although its function was much more than just transport.
"It’s got strategic importance," said Margaret. "It’s in a military zone and it’s proclaiming the power of the empire."
Built of earth and boulders, the south-east side was protected from the river by a massive retaining wall, 19 metres long and consisting of huge stone blocks, up to a ton in weight.
The massive blocks were not set with mortar, but bound together with metal clamps - a type of construction that was also common in Ancient Greece.
This map gives some idea of how the course of the River Tyne has changed and just how big the bridge once was. © Tyne and Wear Museums.
Margaret and her team have now unearthed the full extent of the wall, as well as a massive ramp, almost 12 metres wide, which would have carried the road up to the bridge.
They also found a huge decorated octagonal stone, thought to be the capital from a pillar or monumental feature, which once marked the point where the road rose onto the bridge.
Discussions are now in progress with various agencies to decide how a display could be created at the site to allow public access to the remains.
Although it is very much at the planning stage, ideas include boards with diagrams and information about what the bridge would have looked like, as well as preserving as much of it as possible in its original position.
"Although there are timber bridges in the south of England, it’s only in the north that we get stone bridges," explained Margaret, "so it really is classical architecture. It must have been quite a stunning thing in its time."
The next step in this ongoing project is to work out how best to display the ancient material. © Tyne and Wear Museums.
As well as what it might have looked like, work at the site also revealed what could have happened to the bridge in post-Roman times.
Experts believe the river, whose course has swung through 45 degrees since the Roman period, eroded a deep gully causing three layers of masonry in the retaining wall to fall away.
Blocks were then robbed from the standing remainder of the wall and the metal clamps prised from their slots.
The Anglo-Saxons who did the robbing are thought to have used the blocks for their own buildings and were so impressed by their size they dubbed them 'the work of giants'.
Research suggests that masonry from the collapsed bridge was used for the crypt of the church built by St Wilfrid in Hexham in AD 674.