There is an appropriate grandeur to the place, as befits a building which by chance has been finished just as Scotland achieves devolution from the UK. Amazing to think that back in 1991, the Scottish museums establishment saw this place as merely an extension to the existing, grandly Italianate 1861 Royal Museum next door, and did not even want the new place to have a separate entrance. Benson and Forsyth, however, always knew that their baby would have its own character, always had that entrance bastion in their designs. And, of course, everyone saw sense eventually. The old and new museums are still linked, but we may well find that the old one becomes an extension to the new, rather than vice-versa.

This is not least because the moment of arrival in the new museum is given such drama. From the vestibule of the drum on the corner, you move through a long, narrow hall, finally emerging into a great covered triangular courtyard of epic scale, rising the full height of the building. This space is overlooked by various mysterious architectonic forms, all fulfilling some function or other on the upper levels. The stone of the outside walls continues through on the floor. Walls are in white unpainted plaster, open-tread stairs in concrete of Japanese silkiness. Further up, the floors change to limestone and white-stained ashwood makes an appearance. The architecture tries to be recessive: the idea is that when the lighting is properly sorted, it is the objects that you will see, not the surrounding building. Well, this laudable aim might work in isolated galleries but there is no way visitors are going to become unaware of the nature of the building they're in.

After all, you cannot ignore the interior of 19th century marvels such as Alfred Waterhouse's Natural History Museum in London, or, come to that, the Crystal Palace-like galleries of Francis Fowke's Royal Museum next door in Edinburgh. Only curators worry about architecture stealing the show. Given their own way, most curators would still opt for the "black box" approach. The public, however, wants more of an all-round experience. These days, the architecture is the show. Why else would anyone travel to Bilbao to see a Guggenheim Museum?

So the Museum of Scotland is very vigorous stuff for Edinburgh, a city which has long had a more puritanical attitude to architecture than its rumbustious industrial neighbour, Glasgow. But what do you expect? Gordon Benson, though London-based, is a Glaswegian, and his parallel lifelong love-affair with the Scottish capital can never take that away from him. His is the background that produced the formidable architects Alexander "Greek" Thomson, Charles Rennie Mackintosh, and in the 20th century Jack Coia with his sequence of Catholic churches.

Benson, a wiry man in his fifties, is a bundle of nervous energy, counterbalanced by the calmer influence of his partner. Both - and again, this is unusual - have spent inordinate amounts of time up in Edinburgh, ensuring that the Museum is built as they want it to be. They do not like to delegate, they have continued to design throughout. With only a couple of weeks until the official opening by the Queen on St. Andrew's Day, November 30, Benson and Forsyth were both to be found crammed into the tiny site office behind their museum, still issuing the latest of untold thousands of design drawings. This is a very old-fashioned and thoroughly uncommercial approach. Let's be thankful that some architects still believe more in getting the building right than they do in maintaining the profits of their practice. As for the opening, that will be a Sadler's Wells kind of affair. They'll still be finishing this place off well into next year.

This place is as much to do with making history as it is do with presenting history. Whether by luck or judgement, it has arrived at exactly the right political moment. Its grandeur is appropriate for the new importance of Edinburgh as a power base. Normally, where power goes, culture follows. But in this case, culture has anticipated power. So when you get to go round the new Museum of Scotland, consider not so much what it is, but what it stands for. Consider the interesting times that lie ahead for its country. And then consider what those interesting times will yield in the form of materials for a national museum. So the museum collections somehow managed to neglect the 20th century? Well: perhaps the 21st century can put that right.