Just three years after Belfast's arts venue The Mac opened its doors, stonework at the entrance of the £18m award winning building has begun to crumble.
Large chunks of basalt stone tiles have fallen from the exterior of the six-storey arts venue, situated in the city's Cathedral Quarter.
Contractors have been called in urgently to assess the extent of the damage and carry out necessary repair work.
The visible deterioration of parts of the building, which only opened in April 2012, has sparked concern.
Calls have now been made for a probe into the cause of the damage and for an estimate of how much repair work is likely to cost.
"It is a matter of great concern that within a few years of the Mac opening it appears that parts of the building are degrading," SDLP Belfast councillor Tim Attwood said.
He added: "It is essential that there is a full investigation into the cause of the problems, how they can be remedied and why a new building could degrade so quickly."
The Mac said that work is currently under way to identify the cause and scale of the problem.
"An issue with the basalt cladding of the Mac has been identified and remedial works have been completed," a spokesman said. "The work currently being undertaken to the Mac's façade is to identify the cause and scale of the issue."
He added: "Specific information on the costs and timescale for repair will become clear in the coming weeks."
The building was designed by Hackett Hall McKnight Architects and was built with Belfast brick and Antrim basalt.
Nobody from the architects firm, now known as Hall McKnight Architects, was available to comment about the problem when contacted by the Belfast Telegraph.
The arts venue boasts two theatres, three visual art galleries, a dance studio, workshops, a cafe and a bar.
In 2013 the building was recognised for its architectural excellence with a National Award by the Royal Institute of British Architects.
The cost of the venue, which was 10 years in the planning, rose from £9.2m to £17.6m, leading to criticism of the Department of Culture, Arts and Leisure by the Audit Office for allowing the project to go over budget.
At the time the Mac said that from the initial concept and the start of the actual tender process, the scale and scope of the project "had changed significantly".
More than 600,000 people have visited the flagship arts venue since it opened, according to Mac figures.
The venue is currently on the shortlist for the prestigious Art Fund Prize for Museum of the Year, along with London's recently renovated Imperial War Museum, Manchester's Whitworth Art Gallery, The Tower of London, Oxford University Museum of Natural History and the Stamford Military Hospital at Dunham Massey.
Singer and TV presenter Ana Matronic recently described The Mac as "the most amazing and unexpected piece of architecture, like a red-brick Escher puzzle crowbarred into the heart of a newborn city".
She added that The Mac "is a breathtaking new addition to the Belfast experience, a communal and democratic space that encourages the young and the old to learn, laugh and grow through art".
Leading playwright Martin Lynch, however, caused controversy last year when he launched a scathing attack on the venue, branding it elitist and out of touch.
He accused The Mac of middle-class snobbery and having more interest in hosting the latest plays from Edinburgh or London than in backing local talent.
The £18m Belfast Metropolitan Arts Centre opened its doors in the Cathedral Quarter of the city in April 2012. The building, which is funded by the Department of Culture, Arts and Leisure, was initially due to cost £9.2m to construct. It contains two theatres, three visual art galleries, a dance studio, workshops, a cafe and a bar. In 2013 it was recognised for architectural excellence with a National Award by the Royal Institute of British Architects. The venue has now been shortlisted for the prestigious Art Fund Prize for Museum of the Year 2015.