For Gio Ponti, architecture was a crystal: a definite, finished work of art that needed no perfecting. The relationship between architecture and structure was likewise one of crystalline purity, defining what should remain visible, and making inventive use of materials and technology to solve issues of construction and duration. Architecture and structure were an inextricable amalgam. For Ponti, the Pirelli skyscraper (1956-1960), a symbol of modern Milan, exemplified this concept.
Ponti developed his project with Rosselli and Fornaroli, and the Valtolina e Dell’Orto practice, co-opting Nervi and Danusso for the structural aspects. The skyscraper’s architecture was designed to epitomise levity, longevity, stand as a prestigious blend of technology and form, and be new urban landmark – also at night. The sail atop the roof, the ceramic mosaic cladding on the visible structural frame, the aluminium and glazing curtain walls were all formal and technical innovations at the time. The sweeping, pillarless interiors allowing modular spatial distribution were supported by a structural system comprising two pairs of central transversal walls and, on the sides, four, clearly visible, sloping slabs. Headquarters of the Lombardy Regional Authorities from 1978, the building underwent several refurbishments. On April 18, 2002, a small aircraft crashed into the 26th and 27th floors, causing casualties, inflicting severe structural damage and destroying the curtain walls. It was decided that any repairs should not simply replace the beams and radically alter the façades but preserve the original design concepts and materials. Which amounted to a modern architecture restoration project. Commenting on the 2006 Milan Triennale competition for the “Gold Medal for Italian Architecture”, Arata Isozaki described the Pirelli project as “a perfectly executed restoration of a building that remains an example of superior quality architecture – an historic, yet wholly contemporary architecture”. Restoration along these lines is, however, a complex business. In this case, the damaged aluminium profiles had to be restored, the mosaic of ceramic pieces cladding the  façade assessed for damage, restored and replaced where necessary, the structural framework reinstated, the beams strengthened with post-tensioned steel cables, and the floor slabs reinforced with carbon-fibre sheets.
Restoration was accompanied by two refurbishment projects: the Auditorium, and the “Belvedere”, the panoramic 31st floor. International competitions called in 1998 awarded the first project to Corvino+Multari, and the second to Renato Sarno, who co-ordinated the whole restoration project.  Corvino+Multari’s refurbishment of the underground Auditorium has created a Convention Centre of approximately 1.000 sqm. The project preserves Ponti and Nervi’s original sequence of unconcealed beams in the meeting hall. A new entrance, a specular version of the original access, connects the foyer to the road, cutting across the raised garden towards the square and providing easier access to the Convention Centre. New vertical circulation routes connect foyer, auditorium, services and ancillary spaces. In the congress area, circulation routes depart from a filter area near the main 348-seat meeting room where a staircase and lifts lead up to the original, double-height foyer and reception. In the auditorium, the original staggered seating has been maintained but the floor gently raked for better visibility of the stage. The entrance and hall are clad in makoré wood. Floors are in wood, light coloured rubber combined with accessories in satin-finish glass and steel. On the outside, a new entrance dialogues with Piazza Duca d’Aosta, its cantilevered canopy reaching out towards the public square. The second, Belvedere, project by Renato Sarno reinstates the top floor’s original function as a panoramic terrace with its structural framework deliberately in full view.
Restoration has respected the Pirelli building’s unity, slender structure, transparency and flexible interior distribution, famously corroborated by furnishings that mould to the architecture. At the same time, however, the building has been brought in line with current safety and energy saving standards. The original architectural solutions were maintained, and the curtain walling and ceramic lozenge cladding reinstated using state-of-the-art techniques. All improvements in distribution and technical plant installations rigorously respect the original spatial distribution.
New ceremonial areas (entrance onto Via Fabio Filzi), and serial office spaces have been created. The underground plant and services area - “the engine room theatre” as Ponti liked to call it - are more readily accessible while the entrance from the mound or “Collina” from which the skyscraper springs has been repaved with a combination of porcelain stoneware and special rubber tiles.

Francesco Pagliari