You enter the building via a lobby at the far end, which has the "Green Room" café above it. Given the very different activities contained within the building, the first thing that strikes you is the quality of natural light, in both offices and industrial spaces. Ritchie's details are appropriately tough, for this is a building designed for rough treatment. The interior proportions are noble, generated apparently by the dimensions of a stage backcloth stretched to full height. Simple but effective tricks are played, such as Ritchie's use of supergraphics to mark out certain specialist areas of the factory floor - the paint workshop, the dirty zone and so forth.

In the rehearsal pods, one of which is set aside for schools groups, there is a calm atmosphere generated by the fact that you are standing slightly sunk into the ground, with the windows - set very low outside - meeting your eye level inside. So the pods are taller than they first appear. Floors are sprung (a lot of dancing goes on), walls are white, with black curtains you pull round to adjust the acoustics.

It will be interesting to see how TR2 develops as a place for the public to go. When the final interior fit-out is completed, you will be able to walk through the building along a glazed upper-level corridor and see the backstage work of the Theatre Royal in progress, laid out dramatically below you. These are said (by the theatre's management) to be the finest such production facilities in the world. There may be some thespian hyperbole there, but they are certainly they are the best I have ever seen.

What TR2 tells you, however, is not so much that architecture can do good things for the theatre, but that architecture can do good things for industrial buildings. Had this centre been making car parts rather than musicals, the chances of an architect of Ritchie's standing being appointed would have been minimal. The well-designed factory is becoming an endangered species. But this is one of them.

Website of Ian Ritchie architects: www.ianritchiearchitects.co.uk