The elements of architecture which most fascinate Renzo Piano are 'curiosity, social tension, the desire for adventure. These are the things that have always kept me outside the temple.' Piano is an architectural outsider by definition and by choice. 'If I have to compare myself to someone,' he declared when receiving the Pritzker Prize in 1998, 'I prefer Robinson Crusoe, an explorer capable of surviving in foreign lands.'
Born in Genoa in 1937, the son of a building contractor, Piano studied architecture in Milan and worked for a time in the office of Franco Albini. Yet from the first, his interests diverged from the urban and historicist preoccupations of post-war Italian architecture. Among Italian masters, Nervi was his greatest inspiration, though Buckminster Fuller and Jean Prouve (who liked to be known as a 'constructor') were even more potent influences on the young Piano.
In 1971, Prouve was on the competition jury which, having scrutinised 681 entries, awarded Piano (and his then partner, Richard Rogers) the task of designing the building where this large, elegant and engrossing show of his work can now be seen. The exhibition coincides, of course, with the re-opening of the centre after a two-year restoration and refurbishment project in which Piano has played the lead role.
The most important outcome of the Paris project for Piano was the beginning of an association with the great engineer Peter Rice, terminated only by the latter's untimely death in 1992. Rice further fuelled Piano's experimentalism, which extended beyond merely technical and aesthetic issues into an examination of the basic components of Modern architecture and, in particular, a re- examination of the nature of materials.
The Pompidou Centre was, in a sense, an act of homage to the metal and glass constructional tradition of the nineteenth century. Piano's travelling pavilion for ibm mixed aluminium, polycarbonate cladding and laminated wood. Timber became a preoccupation, but, from the late 80s on, terracotta and natural stone too became part of Piano's vocabulary.
His office was permeated by what he called 'a culture of doing' which underpins his romantic functionalism. Piano's use of load-bearing stone arches for the Padre Pio church at San Giovanni Rotondo represents a logical approach to enclosing the large open worship space demanded by the brief. It is also 'a precise formal choice' (Piano concedes), part of an urge to push the exploration of materials to its very limits. The Tjibaou cultural centre in New Caledonia saw Piano confronting an unfamiliar building tradition and learning from it, welding together timber and other vernacular materials with concrete and steel to produce one of the most startling buildings of the late twentieth century.
Piano's willingness to learn, as well as to experiment, has made him the ultimate Modern regionalist. Two of a series of outstanding art museum projects, the Menil in Houston and the Klee Museum in Berne, Switzerland, demonstrate his conviction that the modern museum must be a community building, integrated into its context - whether natural or man-made.
The Pompidou show - laid out, like his memorable 1989 exhibition at the riba, on flat tables and featuring drawings, models, components and cad presentations - focuses on three themes in Piano's work: inventiveness, urbanism, and 'le signe du sensible'. The last category includes projects characterised particularly by their response to place and time - they range from the mise-en-scene of the 1982 Calder exhibition in Turin to the Beyeler Foundation at Basel.
The show is partly a (far from exhaustive) retrospective, partly an update on what Piano has in store for the future. The Sydney tower, currently nearing completion, is exploratory and innovative in a way that the Potsdamerplatz blocks, for all their merits, could not be and is unashamedly in the spirit of Utzon. The forthcoming Rome concert hall suggests that one fruit of Piano's work in Berlin is an admiration for Scharoun. It seems an age ago that Piano was identified with something called High-Tech.
The Pompidou Centre itself was the extraordinary product of a unique moment in French cultural history. For all its popularity with the public, it was an embarrassment to the French establishment - a fact reflected by its increasingly dilapidated condition in recent years. The refurbishment is largely uncontroversial, though Richard Rogers has lambasted both the imposition of charges for the escalators and the (related) intrusion of a new internal escalator bank serving the heavily-used library.
Perhaps it is too early to judge, but the mood of the place seems to have changed. Security is to the fore and there is an implicit understanding that the piazza will henceforth be a far more regulated space. Perhaps the spirit of 1968, which infused the competition scheme, has finally evaporated.
Kenneth Powell is an architectural journalist