I remember the British Museum fiasco well. Unfortunately, the screw-up was not noticed until the majority of building work had been completed, and rather than stop it, apportion blame, and get it changed, it was a case of "Oh well, it's a bit late to mess about with it now" and the project continued. A bit of digging unearthed some of the Evening Standard articles that exposed the farce, this being reasonably typical:

"The British Museum was the victim of a scam over a crucial part of the £97 million millennium project to open up its great courtyard, an Evening Standard investigation has revealed.
English Heritage, Lord Foster's architect practice and several experts were taken in by a flamboyant Dorset stonemason who put in a cheap tender to build the south portico. The Queen is to open the new courtyard in December, and the museum and stone experts are frantically trying to correct the portico's mis-matched colour and texture.
The museum believed the portico was being built in Portland stone, to match the original material of Sir Robert Smirke's Great Court of 150 years ago. But Easton Masonry, the company which won the contract, mixed samples of Portland stone with a cheaper French limestone to get approval - and then secretly went ahead with building in the French stone. The result has appalled experts. The portico is dazzling white and stands out from the Portland stone that surrounds it. "We were mugged," said the museum's managing director Suzanna Taverne.
Today, a crisis meeting between the museum, English Heritage and Camden council - which must give the ultimate planning approval for the Grade 1 listed building - is being held to try to solve the problem. When the museum confronted Easton Masonry's owner, Geoff Smith, he denied using foreign stone. Then, after a series of scientific tests he admitted the switch that had the potential to save him tens of thousands of pounds.
The museum, English Heritage, Foster and Partners decided not to reveal the deception, which has been known about by insiders for more than a year. But inquiries by the Standard uncovered the scam.
Ultimately Camden could order the portico to be pulled down and rebuilt. Easton Masonry refused to comment."
http://www.museum-security.org/00/142.html#3

And was it pulled down and rebuilt? Three guesses...