THE Mackintosh building at Glasgow School of Art was the result of an architectural competition.

In 1896, the city firm of Honeyman and Keppie submitted a design from one of their junior draughtsmen, Charles Rennie Mackintosh, for the contest. The budget was £14,000.

The first half of the building was completed in 1899 and the second half 10 years later. The 1909 intake of 1000 students - full and part-time - produced artists, draughtsmen, designers, architects and painters.

More than a century after it opened, Mackintosh's School of Art remains a working building.

It is also increasingly seen as an important architectural monument in its own right and is an A-listed building.

With growing interest in Mackintosh and Glasgow, the School of Art - recognised as one of the architect's masterpieces - is visited by more than 20,000 people a year.

It is home to an extensive range of furniture and fittings, watercolours and architectural drawings by the architect who gave it his name. The school also owns a substantial collection of work by former staff and students and a large archive.

In 2007, a rolling programme of work, costing £8.7 million, began to upgrade the historic building.

Administration offices were moved and restored as studio spaces, extra gallery space was added and its archive was extended and preserved.

In 2009, the year of its centenary, a nationwide poll by the Royal Institute of British Architects (RIBA) voted it the best building of the past 175 years.

It won ahead of the Pompidou Centre in Paris, St Pancras Station and the Natural History Museum in London.

Stephen Hodder, president of RIBA, said last night: "The most important work by Charles Rennie Mackintosh, an architect of international significance, Glasgow School of Art is held in the highest regard by architects and the public alike.

"Damage to a building of such immense significance and uniqueness is an international tragedy. It is irreplaceable.

"The RIBA joins our colleagues in Scotland in sending out a message to the students, staff of the school and all those who have been associated with this building over the decades, a message of sorrow and commiseration at this terrible news.

"It is too early to talk about what happens now, but the institute will do anything it can to help in any way."