Contrapuntal composition: Rudy Ricciotti's concert hall in Potsdam sensitively and imaginatively reconciles a new building with fragments of the city's Prussian past and its recent darker history. (Interior Design).

Rudy Ricciotti has shown himself adept at working with old structures. His scheme for the Visitors' Centre at Aries (AR March 2002), treasures the past, and makes the new impinge as lightly as possible on the old. Such an approach, which has long and honourable traditions, becomes a problem when the recent past is a disgrace and every instinct dictates its obliteration. In old Potsdam, the site of Ricciotti's Brandenburg Philharmonic concert hall, history is a potent force embracing an aristocratic Prussian past and more recent sombre events. It is interesting to note in passing that Ricciotti is the first French architect to build in Potsdam since the residence of the enlightened Frederick the Great (1742-1786) and his French-speaking court.

The Brandenburg Philharmonic is in the residential heart of old Potsdam, screened from view along Wilhelm-Staab Strasse by apartment buildings restored after the fall of the Berlin Wall. In the midst of its Baroque surroundings, it is a sober presence with severely tailored faces clad with concrete fibre panels under a copper roof. But its overall severity is disturbed by detail; by random openings, and copper window cills which tilt at wildly differing angles. Surreality is heightened with the realization that the building's austere and sinister annexe is a legacy of National Socialism and remnant of the Nikolaisaal, old Potsdam's parish hall.

It was built by Richard Herzner de Zehlendorf at the beginning of the twentieth century, but then altered in 1933 by Hans Dustmann, architect to emerging Hitlerites. First used for meetings and choir practices, its hall was adapted for worship when Schinkel's Nikolaikirche was damaged during the Second World War. Restoration of the church rendered the Nikolaisaal redundant and, considering its existence a standing reproach, the town council decided to pull it down and construct a concert hall in its place. Thrown open to competition, the commission was won by Ricciotti with the surprising proposal to accept, rather than deny, the marks of history, by retaining the main part of the Nikolaisaal as a lobby to the new concert hall.

You experience the building as you would a contrapuntal composition. From Wilhelm-Staab Strasse, you pass through a large doorway in the eighteenth-century street front into a courtyard, through glass doors bearing extraordinarily festive gilded handles, and into festivity's counterpoint, the dark colonnaded void of the Nikolaisaal. Stripped down to the essential rationalist structure, the lobby has stark columns rising two storeys high and encircled with light top and bottom. An equally stark gallery, running at first floor level around three sides of the hall, provides an upper foyer and bar (furnished surreally with Philippe Starck's white armchairs). The lobby is made more cavernous and raw by treatment of enclosing planes. Walls, floor and ceiling are covered with subtle variegated pigments applied in thin layers so that the material underneath shows through (rather as old temple horses in Rajasthan were painted). Colours -- black, green, grey, khaki -- have a translucent shadowy quality, shifting and g leaming as you move under the battery of lights (by Berlin designer, Fred Rubin).

On plan the auditorium is a trapezium rising three levels high inside its rectangular confines with rehearsal and dressing rooms fitted around two edges. Intervening between the Stygian drama of the lobby and the luminous one of the auditorium is a curved strip forming the hall's outer edge. It contains a long corridor off which are washrooms and cloakroom. From the ground and first floors of the lobby, its existence is indicated by a bulging wall of burnished wood, like the body of a stringed instrument.

The auditorium has a sensual, womb-like impact. It is induced by the gentle movements of the various planes -- the undulations of an Aaltoesque ceiling which drops down to meet a shallow stage and converging walls softly pulsating with organic life. Materials (metal mesh and plaster) and forms are shaped by acoustic and technical imperatives (reverberation time caters for chamber and symphony orchestras, and opera), but in extemporizing on the functional, Ricciotti has produced something of great poetic drama. Lighting is soft and, diffused across the undulations and billows, casts curving shadows. An occasional billow is surrounded by a neon aureole while, here and there, a direct spot of luminance is thrown by a stage light.

In accepting history, Ricciotti has been neither sentimental nor patronizing. The old has been expressed as old, the new as new. What remains of the Nikolaisaal has become an archaeological fragment, its ambivalent status suggested by its reduction to a primitive state and stark shifting planes, a Zeitgeist in powerful contrast to the spirits of optimism, poetry and humour that inform the new building.