The restoration of one of Scotland's greatest modern buildings, which has lain in ruins for 25 years, is to begin in the new year.

The £7.3 million transformation of the A-listed St Peter's Seminary, in Cardross, Dunbartonshire, will convert its ruined main chapel into a 600-capacity arts space, create a series of indoor and outdoor educational areas, and reclaim woodland and paths in its 144-acre estate.

The seminary, occupied for just 14 years for its original purpose until 1980, was designed by the late pioneering architects Isi Metzstein and Andy MacMillan for Gillespie, Kidd and Coia.

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The Glasgow-based cultural charity NVA is leading the redevelopment of the seminary and the surrounding Kilmahew estate, with a design team involving London-based architects Avanti Architects, the Glasgow-based ERZ Landscape Architects and Nord Architecture.

After it closed as a seminary, the building was used for five years in the 1980s as part of a drug rehabilitation unit and the buildings then fell into a state of disrepair.

In 1993, the then Secretary of State listed it as being of special architectural importance. The World Monuments Fund added St Peter's to its register of most-at-risk buildings in June 2007.

Now the building, long considered a modernist classic, is to be given a second life. The redevelopment will be completed by 2017, 50 years after the first stone was laid.

The seminary buildings themselves will not be completely rebuilt. The famous chapel will have its altar remove to become a 600-capacity arts venue.

For the first five years of its new life it will be a base for artists, teachers, students and audiences, NVA hopes.

There will be an annual summer events calendar as well as what is being called The Invisible College, a collaboration with Scottish universities, art colleges, local people and artists.

The first work will be removing significant amounts of asbestos, which will begin in early 2015. A large area of "invasive rhododendron" has already been removed from the parkland.

An inaugural illuminated ­landscape event will be held in spring 2016.

Overall the plan will cost £7.3m and so far £5.5m has been secured from the Heritage Lottery Fund, Creative Scotland, Historic Scotland and Argyll & Bute Council.

£1m has come from private donors, and contributions from the Architectural Heritage Fund, Binks Trust, Dunard Fund, Hugh Fraser Foundation, Mickel Fund and Pilgrim Trust.

Angus Farquhar, creative ­director of NVA, said the plan did not envisage "turning the clock back to 1966" but working with the ruins as they stand now. Of the asbestos removal, he said: "It will take around six months to remove - this is not a benign old building."

He added: "NVA's plans ­represent an unheralded form of regeneration; one that accepts loss and ruination as part of the site history.

"Our plans offer a singular and dramatic set of spaces to release new uses and new ways of framing human activity."

He added: "So much of our learning, from childhood onwards takes place indoors in dull, stifling environments. So why not spend time somewhere that feels like a day off from your ordinary life?"

Murray Grigor, the film maker who made a documentary, Space and Light, about the building, said: "Without the courage to intervene, the one masterpiece of late 20th century Modernism in these islands was sinking into an irreversible death.

"If anyone can reverse the lamentable neglect of the past decades it's surely NVA, whose indefatigable resolve I have admired in bringing so many seemingly impossible ambitious projects to life.

"The challenge for the young secular architects Isi Metzstein and Andy MacMillan was how to translate the ecclesiastical traditions of a thousand years into a modern language: their success in achieving this fusion in their own masterpiece is surely worthy of preservation."

NVA aims to raise an additional £1.8m by the end of 2015.