The forthcoming History Centre in Durham has been delayed "due to unforeseen building work", councillors have been told.
Durham County Council is restoring the manor house and turning it into a new attraction.
The "vibrant and interactive local history hub" will bring together archive, heritage and registration services.
However Durham County Council's environment scrutiny committee was told of delays to the project this week.
Tom Gorman, corporate scrutiny and strategy manager, said at the committee meeting: "The History Centre has been delayed.
"That was due to unforeseen building works which were required.
"Mount Oswald, the old manor house, is a Grade II listed building so those building works will take a little longer than normal."
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A council report stated: "Due to unforeseen issues to the listed building which involved additional works on the stonework and roof, the History Centre has been delayed.
"This will extend the construction programme beyond the original completion date of October 2022.
"New timescales are currently being reviewed."
Alison Clark, head of culture, sport and tourism at Durham County Council, said today: “When restoring historic listed buildings, it is not unusual for unforeseen works to arise during the process.
"We have discovered additional building works are required at Mount Oswald and are carrying out detailed studies to ensure these can be completed in accordance with listed planning consent.
"We remain confident the new History Centre will open to the public in 2023 as originally planned.”
At the committee meeting, Councillor Eddy Adam asked about the additional costs of the building work, with more information to come at a later date.
Mr Gorman spoke of the area's performance in tourism and the visitor economy.
He said: "The number of visitors, the number of jobs and the money generated by the visitor economy, they're all down in comparison with the previous year.
"And that's largely due to the effects of the pandemic.
"However there's an ongoing survey that Visit County Durham carried out which shows some greater confidence from businesses in the visitor economy around the number of enquiries and bookings they've had.
"Nevetherless forward bookings do remain below average in comparison with previous years.
"That might be a reticence of people to book up early, we think, so it's something we'll have to keep an eye out for.
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"The survey also reports on recruitment and supply chain issues, and some businesses are reporting a lack of demand.
"But I think it's a cautious picture from that survey. There's some good points and there's some bad points."
He pointed to Lumiere which attracted 180,000 visitors in November last year, including six locations outside the city.
Councillor Jonathan Elmer asked how the "looming cost of living crisis" might affect the visitor economy.
Mr Gorman replied: "I'm an eternal optimist.
"I think it could have a beneficial effect in that people may not have as much money to spend on foreign holidays and may be seeking to travel within the country.
"I think if we were to win the City of Culture bid, that would certainly be something that would increase the attractiveness of County Durham to people within the UK."
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