The Scottish Parliament, with its Scottish Kemnay and South African Belfast Black granite cladding by West Lothian stone specialists Watson Stonecraft, has won the prestigious RIBA Stirling architectural prize.

The presentation of what is considered by many to be the UK's top architectural award took place at a ceremony at the Royal Museum, Edinburgh, televised live on Channel 4 on 15 October.

Although the building, designed by the Spanish/Scottish consortium of EMBT/RMJM to a concept by the Spaniard Enric Miralles, who died in 2000, was finished three years late and ended up costing 10 times the original estimate - although that estimate has been criticised for being unrealistically low - it has become appreciated and respected as an iconic building housing Scotland's first parliament in 300 years.

Graeme Haddon, managing director of Watson Stonecraft, said when the building was featured in NSS in January this year: "We will always be happy to have been associated with it. It will be judged on its merits - it's definitely landmark architecture."

The Stirling Prize judges clearly agreed. They commented: "The Scottish Parliament Building is a remarkable architectural statement which has an enormous impact not only on the visitors to the building but also on the users who repeatedly move through a series of extraordinary spaces and their changing effects.

"That a project has outlived both its original client (Donald Dewar) and its architect (Enric Miralles) and still got built and built well, is very much down to the vision and dogged determination of one man: chief architect at the Scottish Executive, John Gibbons.

"This is his building every bit as much as it is Dewar's. He was the man who had to ensure that the original vision of two men who had achieved instant sainthood on their deaths and whose work could therefore not be touched, could be realised… and afforded.

"The proof of the extraordinary architectural ambition and design vision is to be seen in every aspect and detail of the finished building. At the outset, Miralles made a major contribution in leading the clients towards a proper understanding of their needs and the final formulation of the role and function of the building. Further, through his awareness of the problems and knowledge of the subject, the architect has formulated the philosophy of the role of the Parliament and reflected it in his architectural interpretation.

"In its context the building manifests itself as an attempt at an organic transition between the city and the drama of the Scottish countryside surrounding it. An extremely successful landscaping makes this transition even more striking.

"The building is a statement of sparkling excellence. On the Memory Wall one of the statements reads: "Say little and say it well". This building is definitely saying a lot rather than little but it definitely says it well."

Jack Pringle, President of the Royal Institute of British Architects, presented Benedetta Tagliabue, Enric Miralles' widow, with the Prize and the £20,000 that goes along with it.