Charles Rennie Mackintosh’s School of Art, completed in 1909, is one of the greatest buildings in Scotland if not in Europe. In a year where the Scots are going to vote on a proposal for independence, it is slightly sad that it is an American architect who was commissioned to carry out the extension to the School of Art. Where is the Scottish talent? To his credit, Steven Holl has created a superb set of interiors where every floor is different, with light (so important in art schools) cascading in a variety of ways through the building. Externally, this must have been the commission from hell; the Art School did not want a pastiche of the old building – quite rightly – but how could any architect compete with Mackintosh. The original proposal before Holl was commissioned was ugly and severely criticised. Holl’s exterior for the new building, named after Professor Seona Reid, former director of the School of Art is simple, clean and crisp, an clever and interesting contrast to the weathered stonework of the original building. It oversails and envelopes an existing building which is quite fun and does appear to work through a visual separation from it. The way to see this addition to the Glasgow landscape is exactly as that. Not an extension to the Glasgow School of Art, but a stand-alone modern building of international quality. This variety of architecture, fitting into the grid of streets, reminiscent of New York, is one of Glasgow’s strengths and New York-based Steven Holl has responded well to that. It is also a building that should weather well in the harsh wet Glasgow climate.