ITS stateside appeal was highlighted when former Hollywood golden couple Brad Pitt and Angelina Jolie were granted a special private tour of Charles Rennie Mackintosh’s Hill House masterpiece.

Now the National Trust for Scotland is hoping for a trans-Atlantic funding boost by taking its campaign to the US to raise money to conserve the historic Helensburgh property famous for its integrated architecture, interior and furniture design.

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The push comes as the property that sits high on a slope overlooking the Firth of Clyde faces increasing water damage penetration resulting from the architect and artist's experimental building techniques.

The trust said the conservation project will have an impact on the treatment of early modern houses around the world.

The separated A-listers Pitt and Jolie visited the house in happier times in 2011 during a break in Pitt's filming for the zombie movie World War Z in Glasgow

It was Pitt’s second visit to Hill House who went there when he was filming Interview with a Vampire in 1994.

The National Trust for Scotland Foundation USA is now expected to play a key part in the multi-year project that will result in a long-term maintenance and repair methods.

The conservation of the building's exterior will take place in full view of the public so that visitors can experience firsthand the painstaking, groundbreaking work that goes into preserving an irreplaceable piece of architectural history.

The project has been backed by the prestigious Getty Foundation, which has awarded the trust a grant for its work.

The preservation of the Hill House will have an impact far beyond Scotland, as the conservation of 20th-century buildings and materials - which often do not respond to traditional techniques - present challenges for preservationists worldwide.

Kirstin Bridier, executive director of the Boston, Massachusetts based NTSUSA, said: "We are thrilled to have the opportunity to help the National Trust for Scotland preserve Mackintosh's masterpiece The Hill House, truly one of the most remarkable early modern houses in Europe.

"Mackintosh was a contemporary of Frank Lloyd Wright, and the two shared many artistic inspirations.

"We are confident that Americans who are interested in architecture, interior design, and Scottish heritage alike will support this urgent conservation initiative."

Simon Skinner, Chief Executive Officer of the National Trust for Scotland, said: "When thinking of Scottish buildings, many Americans will understandably picture ancient castles and historic houses in ancestral homelands, and they have given very generously to help conserve them.

"In this case we have something very different, but no less deserving of support.

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"This is an example from relatively recent times when a Scottish architect was leading the world and designing a place that has been a major influence on the way we all live now.

"Charles Rennie Mackintosh's Hill House is simply astonishing, and I hope that our wonderful US supporters can help us care for one of the world's truly visionary buildings."

Built for publisher Walter Blackie and his family in 1902-3, the Hill House remains a remarkably complete example of Mackintosh's unique vision of an arresting mix of Arts and Crafts, Art Nouveau, Scottish Baronial and Japanese influences.