Why? Because it advances the art and science of architecture and engineering. Because it lifts the spirits. Because it does its job well. Because it is alive. Because it is not self-consciously, navel-gazingly architectural. And because it offers a way out of rural paralysis. This is very advanced design, in the countryside. It is a 21st century barn. And what is a barn? It is just a great big covered space. You can use it for anything. This one is a workshop for the Weald and Downland Open Air Museum, near Chichester in Sussex. They re-assemble salvaged medieval timber-framed buildings inside it. But it could equally well be a sports hall, or a factory, or a car dealership, or a supermarket, or an aircraft hangar, or a museum. And it is made of wood. I think we need more buildings like this.