The beautiful piece of land, with the Villa Schöngrün and the Schosshalde graveyard with the grave of Paul Klee in the immediate vicinity, seemed as though created for the construction of a museum which would accommodate the complete work of the Paul Klee Foundation. The idea of combining nature and architecture in an exciting relationship to one another, met with the best premise here.
From the outset it was clear to Piano that the artist Paul Klee has «a too broad, too large breath», for him to be locked up into a «normal building». For the vision of his own work Renzo Piano allowed himself to be inspired by the identity of the place, the gently curved line of the terrain. That the motorway was also there, with a deep cut abruptly restricting the building site, did not disturb him. As a «Life line» of our civilisation it would be properly integrated into the project and find its aesthetic-functional echo here. It is very different at the back of the building: in order that the unity of nature and the architecture is not disturbed, it was also his explicit wish that the area around the building should be used as farm land and not converted into a park.
Renzo Piano noticed that the hills in the foreground stand like scenery in front of the horizon of the wooded hills in the background. The three hills blend as terrain contours with the ground and make the entire area into a landscape sculpture. As an artistic structure in its own right it houses the new cultural institution. Seen from the motorway the unusual roof structure is only visible for about ten seconds. Coming from the park it is not immediately clear whether the three curves are artificial or just natural. Only when in front of the main facade are the dimensions apparent: the middle curve is 12 metres high, the glass front to the motorway over 150 metres long.
The wish that the Zentrum should not only be a «Place of remembrance», but also an interchange between encounter, relaxation and enjoyment, Renzo Piano solved by spreading the Zentrum over three hills. Starting from Klee’s numerous different activities as painter, musician, teacher, writer and philosopher the aim of the Zentrum Paul Klee is to present the artist comprehensively in this complexity. As a result each of the three hills has its own task. The North Hill is used for the practice of art education, for music, the conferences and the workshops, the Middle Hill for displaying the collection and the changing exhibitions, the South Hill for research and administration.
The overall capacity and diversity of the collection make it impossible to show all the works at one time. The particular sensitivity of Klee’s works also prevents any classical type of exhibition, in which the same works are always shown unchanged. Instead the Zentrum Paul Klee presents the works which belong to it in a regularly changing selection of about 120 to 150 works, which each time stand under a changing theme. Two exhibition rooms provide space for constantly new examinations of the works of Klee and the presentation of differing manifestations of visual art.
The construction of the Zentrum is at the same time functional and highly technical. Directly behind the main facade of glass is the public area, the so-called Museum Street. This back-bone zone runs parallel to the motorway, is bright, sometimes noisy and for the visitors the only means of connection between the three hills. On entering the exhibition rooms, the noisy mood changes into quiet observation.
Klee’s works are mostly pencil drawings and water colours, which may only be exposed to a maximum of 50 to 100 Lumens. The main hall in the Middle Hill is a pure artificially lit room, like the exhibition hall on the lower floor of the building. The basic lighting is installed in the vault of the steel girders, which shines indirectly onto the roof of the room. The individual pictures are emphasised by spots. The day-light which comes in through the whole glass facade is controlled and dampened by means of an automatic sun protection system.
One consequence of the building’s unusual geometry is the intricate design used for the 150 metre long glass façade. The façade is divided into an upper and lower section along its entire length. The two façade sections are marginally offset and connected by the canopy (the roof of the Museum Street) at a height of 4 metres above the level of the ground floor. The glass façade measures 19 metres at its highest points, and the largest panes of glass weigh almost half a metric ton and measure 6 x 1.6 metres.
In spite of the impressive dimensions of the three hills large sections of the Zentrum Paul Klee are actually situated on the underground floors. This fact is made clear by the 180,000 cubic metres of earth that have been moved since 15 October 2001, involving some 15,000 truck movements on the site, and by the 1,100 tonnes of steel girders, 1,000 tonnes of reinforcing steel and 10,000 cubic metres of concrete put into place.