Excavation work is under way in the basement of Norwich Castle as archaeologists delve deeper into the historic landmark and the mound on which it stands.
They are two weeks into an eight-week programme which aims to shed further light on the origins of Norwich's stone keep, and their findings will help inform how the £13.5m Norwich Castle: Gateway to Medieval England project, supported by the Heritage Lottery Fund, will transform the keep back to how it was in the days of the Norman kings.
The work, which is being undertaken by Oxford Archaeology East led by Heather Wallis and with funding from Historic England, is the first major excavation in the castle in nearly 20 years and the largest ever undertaken.
It is involving careful analysis of two large areas in the south west and north east of the basement.
Dr Tim Pestell, curator of archaeology at Norwich Castle and part of the Gateway to Medieval England team, said an important part of the excavation work was to gain a greater understanding the different layers beneath the basement.
He said: 'What we really want to try to find out is when some of these levels were built up because at the moment we think we first had a mound built and a wooden castle keep on top of the motte, and then the second castle was built in stone, the one that we have here today, and to do that they had to build a bigger mound to support that stone castle. We would like to date the stone elements of the keep and that is the reason for this excavation.'
He said the pier bases in the basement - which had originally supported the floor for the great hall - and what the excavation work discovers around these bases, was also key to the understanding of the castle's structural history.
Ms Wallis explained further: 'We have got pier bases and architectural features but we do not know where the floor levels were so that is one of the key things we are trying to establish.'
Following on from the excavation work, boreholes will be drilled into the mound to help give a better insight into the make-up of the mound.
The basement is currently closed while the excavation work takes place but there are plans to hold accompanied tours for the public once the work is completed.
OTHER DISCOVERIES
As well as giving greater insight into the original structure of the stone castle, the excavation work could also unearth other discoveries.
Fragments of pottery and animal bones have already been uncovered, and Ms Wallis said the quantity of these finds had been higher than anticipated. She said by cross-referencing the pottery and bones it could be possible to find out more about how people's diets will have changed through the centuries.
The excavation could also provide more information about the castle's history as a prison, with part of a wall already unearthed.
'One of the interesting things about the excavation is that while we are primarily looking at the castle and the mound, there are obviously prison buildings that we may also find more about,' said Dr Pestell. He added there was also a well in the basement that had been put in by Edward Boardman, who had overseen the castle's conversion to a museum, but that this well may also have replaced an earlier well put in for the prison.
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