A glut of architects. A surfeit of architects. Whatever the collective noun for architects is, there sure were a lot of them visiting the Graduate School of Design last week. Following Richard Meier earlier in the week, Renzo Piano, one of the world's foremost architects and the man responsible for the planned revamping of the Harvard University Art Museums, spoke to a packed Piper Auditorium last Thursday. Famous for his work in such major spaces as Houston's Menil Collection, Osaka's Kansai Airport and Paris's Centre Georges Pompidou, Piano's speech attracted so large a crowd that not only was the auditorium packed, but even the secondary broadcast room was standing-room only. People had to be turned away in droves. Perhaps the situation called for an architect.

Despite the cramped conditions and the technical flaws of the secondary broadcast, the Italian architect's one-and-a-half-hour speech went over well with the audience. Introduced as the "romantic architect," to contrast with Meier's classical leanings, Piano lived up to his billing by choosing to speak about his concern for "lightness" and fluidity. Although he did not mention his forthcoming plans for the Harvard museums, and instead spoke only about other recently opened projects, the palpable sense of excitement at architecture's possibilities demonstrated that Harvard's own museums are in good hands.

In Piano's words, architecture involves walking "the knife edge between art and science": One day the architect is a poet, the next day an engineer. That fine edge was highlighted in the first part of his speech, which dealt with his redesign of Berlin's Potsdamer Platz. This enormous, 5 million square foot space resonates with cultural significance, since it is both the former cultural center of Europe as well as the center of tragedy. The Cold War divide between East and West Germany, however, is now a matter for the history books, and Piano's task, as he noted, was to build in six years a place that would restore the site to its pre-war exuberance--in effect, to create a site that both remembers and obviates the past.

While he lyricized the locale, Piano did not forego the practical aspects of architecture. Large urban areas pose complexities for any architect: There is a danger of slipping into a uniform design, ignoring the fact that cities draw life from the evolution of buildings over time. All told, the slides presented certainly showed a city center that avoided that danger, and mirrored the unpredictable and complex interactions of humanity. Built around a recently-opened piazza, the Potsdamer Platz as envisioned by Piano will be a meeting point that encompasses vast differences, where elements of the "sacred," like libraries, meet elements of the "profane," like cinemas and casinos. Even the act of construction, which involved 5,000 workers from all over the world, represented the idea of interaction, particularly symbolic when one considers that the Potsdamer Platz was famous as a site of intolerance. Already the praise is rolling in: Architecture Record said that Piano "single-handedly recaptured the long-lost romance of the skyscraper" with the Debis Tower that anchors the project. At no point, however, was the audience allowed to forget the details, as Piano often went into specifics, such as how the engineering of the Debis Tower allowed air conditioning to be optional (a remarkable feat for a skyscraper) and allowed each person in the building control over his or her own environment.

The acknowledgement of the individual, in fact, was an important motif throughout the talk. As Piano noted, much of architecture lies in the invisible, in the memories and social life generated by the use of the space. What one sees--the physical architecture--is merely the tip of the iceberg. He expanded on this idea of "immateriality" in the last half-hour of the speech, presenting slides of his other works. Piano's work has consistently stressed the importance of space and transparency, or, as he put it, "lightness". The glass of Kansai Airport seems to show the open possibilities that flying offers. His Tjibaou Cultural Centre of New Caledonia, for instance, is naturally ventilated by air currents outside, while the Beyeler Museum in Basel, Switzerland uses glass roofs to illuminate its artworks with natural light.

Museums, it has been said, are the modern cathedrals. Richard Meier's Los Angeles Getty Musuem, Frank Gehry's Bilboa Guggenheim--these are the seats of present-day architectural spectacle and wonder. This year's winner of the Pritzker Prize (architecture's highest award) demonstrated his own ability to generate that sense of wonder. It was, indeed, a grand Piano performance.