'Dig at Sheffield's Castlegate is about unlocking city's future as well as unearthing its past'

That's the view of Joy Bullivant, of heritage group Timewalk, who has written a report on the history of the site and the regeneration potential of the area.

Wessex Archaeology is due to start work on the site in mid-August to see how much remains of the former medieval castle and Ms Bullivant said what happens to the site after was just as important as the dig itself.

She said: "I would love the site to be redeveloped because I really think that it's central to Sheffield's heritage. It links with all the other historical sites across the city too such as Manor Lodge, Kelham Island.

"Castlegate has also got great transport links - with bus stops for most major routes and it's only a short walk from the railway station. But at the moment it's just a hole - and I don't mean that because of the dig - I mean because people don't want to go there."

Ms Bullivant said there was a previous dig at the site in 1920s when the former Co-op building - Castle House - was built and said archaeologists found 'one or two interesting things'.

She added: "What I understand, and i am no great expert, is when they knocked the castle down sometimes they just filled the space in with the rubble and levelled the site a bit so there could be all more than we realised.

"There could even be remains of the wooden castle which was there before they built the stone one."

Ms Bullivant said she had sent a copy of her report, which labels Castlegate as the 'lynchpin' to promoting the heritage of the city, to Sheffield Council and had a 'positive response'.

She added: "We should be making a lot of this dig. This was the biggest castle in the North and it's probably most significant dig for at least a decade."