Malmo masterpiece.

The extension to Malmo city library more than doubles its size and makes it an elegant and appropriate civic building for the post-modern age.

Henning Larsen's extension to the Malmo city library is an exemplary achievement: a major public building, simple and noble simultaneously, created by an architect at the height of his powers. Larsen, a Dane who works just across the Sound in Copenhagen, won the project in a 1992 invited competition with a design that recalls Asplund in its simplicity and generous humanity.

The brief called for an extension of the old library (built as the city's museum in copper-roofed red brick neo-Hansa style by J. Smedberg in 1899). The new pieces are an entrance and foyer area in a drum, and a new block of overlapping squares in plan: a low glass tower wrapped to east and south by an L of what Larsen calls the 'heavy' part - four stories of stacks, study areas and offices clad in stone. The drum is balanced between the old building and the stone and glass cubes to the west and is connected to them by glazed links. A U-shaped entrance court is contained between the two main masses; it opens northwards across a quiet road, Kung Oskars Vag, to the beautiful lake and trees of Kungsparken (the King's Park). Because the scale of the west pavilion is skilfully manipulated by juggling the squares of its plan, a balance is set up between Smedberg's cheery red and green museum and its cream and crystal descendant with the stone-clad drum acting as fulcrum.

As you approach, analogies with Asplund are clear, and are patently intended. The drum is not so big as that of Stockholm public library, nor of course is it contained within a quadratic base; the square windows high up on the Stockholm plinth are transferred to the drum in Malmo, as is the great tall rectangular glazed entrance. And the latter is shorn of its wonderful tapering frame, an echo in the 1920s of Bindesboll's dignified and majestic way of making openings in the blank classical walls of the Thorvaldsens museum in Copenhagen in the mid nineteenth century. Larsen's quotations are not as direct as Asplund's were before he evolved his marvellous fusion of Classical and Modern in the '30s, and the Dane's are informed by a sensibility that is post-modern (in the best sense).

The entrance in Malmo is offset from the diametric axis of the drum, and is designed to make you aware of the organization of the whole place, with old and new wings to left and right, a secondary entrance towards the city in front, and the reception and returns desk informing the space. Nothing could be more different from the powerful entrance sequence in Stockholm, with its tight dark vestibule leading to the majestic stair that draws you almost willy-nilly to the light and knowledge of the lending room in the drum. In contrast to this magical, almost shamanistic progression, at Malmo all is open, clear and generous. Instead of knowledge being approached as a distant treasure, attainable by only one arduous route, you are made aware that it has many facets, and that there are many approaches to it, as is made clear by glimpses of the different levels of the new wing to the right, and the open galleries that connect it to the old building which will be reached by a generous free-standing stair, similar to the one which links entrance level to the new first floor reading room.

If external resemblances between the two libraries are obvious, there are strong internal similarities between the Malmo entrance hall and that of Asplund's '30s masterpiece, the Gothenburg Law Courts. There, galleries surround a basically toplit light-filled space and look down on the public parade and the fine gentle single flight of stairs to the first floor. At Malmo the stair has a landing (presumably required by contemporary regulations) and the galleries cut across the space rather than surrounding it; comparisons are clear, but the volume has an element of mystery which the Law Courts rightly lack. A continuous skylight circles the whole space, so that the volume continuously changes with the time of day, weather and the seasons. The monumental effect of light spilling from on high over the very slightly irregular plaster walls, delicately pierced with little squares of holes in front of acoustic absorbent is heightened (in some circumstances) by shafts of light from the small windows high up in the drum. Larsen's motto in the competition - Scandinavian competitions continue the (sometimes) delightful tradition of identifying entries by motto - was Ljusets Kalender, light's calendar, and the giant sundial-like device of the entrance drum is our first intimation of its realization.

The second is the great library hall which you begin to appreciate as you near the top of the stair from the entrance. The four-storey high volume gradually reveals itself as you go through the comparatively compressed