Plans for a major renovation of the Ulster Museum to transform it into a "world-class venue for the 21st century" would have a "detrimental impact on one of Belfast's most iconic modern buildings", according to heritage experts.
The Ulster Architectural Heritage Society is objecting in particular to a proposal to enclose the museum's cantilevered concrete canopy with glass, saying this would compromise the entrance facade - "one of the glories of Modernism in Ulster".
The society has registered its objections in a letter to the Northern Ireland Planning Service's Belfast divisional office, in the hope that they will be taken into account before a decision is made on the £12 million (€17.7 million) scheme next week.
It cites a 1999 Northern Ireland Department of the Environment policy statement on planning, archaeology and the built heritage, which says listed buildings "can be robbed of their special interest as surely by unsuitable alteration as by outright demolition".
The department said it would normally only grant consent to proposals for alterations to a listed building where "the essential character of the building and its setting are retained and its features of special interest remain intact and unimpaired".
The heritage society pointed out that the planners were also required by a 1991 ministerial order to have "special regard for the desirability of preserving the building or its setting or any feature of special architectural or historic interest which it possesses".
The society said the entrance facade "is internationally renowned for its daring splicing together of old and new . . . it is a sculptural tour de force which should be treasured and remain intact.
"The great cantilevered canopy, which provides shelter for parties of visitors and announces the entrance, is a feature of 'special interest' and should not be filled in. Any change would erode its character and amount to a breach of the planning policy statement".
The heritage society stressed it was not suggesting that listing should require "mothballing" of the building. "Alterations or an extension to include café space could be acceptably sited on the east elevation without sacrificing the integrity of this major architectural event".
Designed by London-based architect Francis Pym, who won a competition for the project in 1963, the brutalist-style extension to the museum is one of 50 buildings from 1950 to 2005 featured in Modern Ulster Architecture, a new book published by the Ulster Architectural Heritage Society.
"Time has done nothing to diminish the power and originality of this extraordinary building which first opened to the public in 1971," it says. "If anything, the passing years have enhanced its standing as the major testament to high Modernism in the province."
The entry refers to "the almost barbaric power of the great cubic projections and cantilevers of the Ulster Museum; it broods over the conifers of the Botanic Gardens like a mastodon" (prehistoric mammoth), saying it was inspired by Dunluce Castle on the north Antrim coast.
Like Sir Denys Lasdun's National Theatre on the South Bank in London, which was castigated by Prince Charles in the 1980s as resembling a nuclear power station, it was typical of what art critic Robert Hughes accurately described as the "culture bunkers" of the era.
"The facade has the geological grain of a quarry face, hewn and sculpted", it says. Completed in 1971, it was Pym's only major building; he resigned from the project before it was finished, giving up architecture to become an Anglican priest.
The renovation of the building is being funded by the North's Department of Culture, Arts and Leisure and the Heritage Lottery Fund. It will give the museum an additional 1,225sq metres (13,186 sq ft) of space on various levels.
Apart from a new entrance with a cafe overlooking the Botanic Gardens, this includes a "Hall of Wonders", new history and natural science galleries and improved learning facilities, providing a "truly world-class venue for the 21st century", according to chief executive Tim Cooke.
"As well as transforming a historically important building, this project will allow us to reach out to a broader and more diverse audience across Northern Ireland," he said. "We are confident that this scheme will build on the already strong reputation of the Ulster Museum".
