The library at Glasgow School of Art has been lost to the fire which swept through the Charles Rennie Mackintosh building on Friday.
Iain Connelly, president of the Royal Incorporation of Architects in Scotland, said the value of the building "goes well beyond Glasgow or even Scotland. It is a work of architectural heritage of world renown and its influence on 20th century architecture is immeasurable. Scotland has seen the loss of an international treasure which reflects the genius of one of our greatest ever architects."
Mackintosh was a 28 year old junior draughtsman at a Glasgow architecture firm when he drew up the designs for the building. The dramatic art nouveau design took 12 years to complete and opened in 1909. The interiors were designed in collaboration with his wife, Margaret MacDonald.