THE architect behind the new £50 million Glasgow School of Art has flown in from New York to oversee the building's topping out ceremony

American Steven Holl joined the traditional celebrations when a building reaches its maximum height by pouring fresh concrete into the top wall of his flaghip project.

Mr Holl then watched the traditional bough of evergreen laurel being nailed on for good luck.

The new building, which replaces the Foulis building and Newbery Tower opposite the Mackintosh Building on Renfrew Street, is phase one of the campus development at Glasgow School of Art. It will house design school studios and offices, technical workshops, digital media labs, lecture facilities, exhibition spaces and student areas.

It is being designed and built in partnership with Glasgow-based JM architects and Arup Engineering, and is one of the most significant buildings under construction in the UK. It is due to open in spring next year.

Uniquely, the new building features three massive circular shafts called Driven Voids of Light.

These are designed to deliver natural light through the depth of the building as it changes with the seasons, while at the same time providing vertical circulation and eliminating the need for air conditioning.

Mr Holl's designs include the Kiasma Contemporary Art Museum in Helsinki and the 2007 Bloch Building addition to the Nelson Atkins Museum of Art in Kansas City, and other buildings devoted to the arts in the US, Korea, China and Beirut. He is also designing a new Maggie's Centre at St Bartholomew's Hospital in London.

He said: "My Glasgow building is my most important project because of its proximity to the Mackintosh building. It is an homage to Charles Rennie Mackintosh, whose inventive manipulation of space to deploy light inspired me to invent the Driven Voids of Light.

"I have never used them before, and I will never use them again, because they come from Mackintosh, who created the most important building in the UK."

He added: "There is a silence in the design of our new building's facade, which we have created specifically out of humility and respect for the man."

Mr Holl, from Seattle, also praised the "unique environment" of the Scottish climate. He said: "I love the weather and the northern Scottish light, which will make this building magical throughout the entire year, from June 21 right through the darkest winters."