ITV News has learned that the cost of expanding the Tate in St.Ives has almost doubled. It was forecast it would cost twelve million pounds, but the latest estimate is just short of twenty.
The temporary closure of the famous venue has also had an unwanted impact on the town - three galleries in just one area have closed.
But the Tate says the revamped building will bring a major boost to the local economy.
The sky high increase has surprised many in the town like businessman Neil Whitham:
The Tate has been closed since October 2015 while the improvements are carried out. Art galleries in the Tregenna Hill area of the town say that's badly hit their trade.
One of them is David Hill who's gallery has been running for four years.
Mr.Hill isn't the only one suffering. 3 galleries in the street have had enough and shut up shop.
The Tate said what it called mechanical and electrical issues prevented it from opening while work was going on.
The Tate has pledged the present building will open next Spring and the extension will be finished in Autumn 2017.