Why a skyscraper? The high-rise building is justified when, concentrating the constructible volumes in itself, it is set back from the edges of the site and leaves room for the traffic and for parking. No more streets like trenches. Moreover, giving up irregular space and concentrating volumes in a single building of precise shape, dictated by reason, means going back to intelligence in construction and in the end giving the buildings a shape without flaws, totally resolved. Ponti wrote this in 1956, that is at the time when the Pirelli building was built — this eagerly awaited European skyscraper, a skyscraper that immediately drew bolts of lightning from historians, both European and American, from Zevi to Banham and by presenting itself, provocatively, with a graphic slogan, provoked the critics to come up with slogans in turn. This small skyscraper, with its lean shape (127.10 m high, 18.50 m deep at the centre, 70.40 m in width), does not stand on a basement but emerges, surrounded by a void that separates it from the low blocks around: like a missile being fired from an underground silo. Its essential form, perceptible from the inside as well, matches the thinness of its supporting structure, in which (as Nervi put it) open season was declared on unnecessary weights.

Looking at the three plans (ground floor, 16th floor, 31st floor), which make up the graphic slogan of the building, one can see how the central pillars taper as the load of the floors diminishes. The building cannot grow any higher just as its plan cannot expand owing to the tapering of the axial gallery at each end, where movement within the building comes to a stop. It is a finite form, derived from a structural invention as Ponti called it. A structural invention whose realization required all the skill of Nervi (responsible with Danusso for the structural calculations: stability resistance to wind in a building in which the ratio of width to height is so small was a problem without precedent for a reinforced concrete structure. Nervi solved it by adopting a gravity system, concentrated in the rigid triangles of the two points pairs of hollow pillars with solid walls and in the four equally rigid central pillars large wall-pillars as well as in the central tower of the elevators. Tests of the structure were carried out on a special model all of eleven meters high. Typical of Ponti was the way in which he compared, in Domus, the building as conceived i.e. the perfect model with the building as constructed. He drew attention to the goals achieved -structural invention, essentiality - as well as to those that, clear in our minds, have not been attained in full - expressiveness, illusoriness. These were the terms he used. Check: Publix Weekly Ad and Kroger Weekly Ad.

Expressiveness: the Pirelli building is vertical at the sides, but the glass facade is dominated visually by the horizontal strips of the opaque parapets and yet, the very thickness of the floors had been dispensed with, by making them taper at the edges. We have managed to preserve a grammatical statement, said Ponti, by keeping the sections of glass adjoining the pillars transparent to show that the opaque strips of the parapets have nothing to do with the structure; but, in Ponti's eyes, it proved impossible to get rid of the detested striped pyjama effect. Illusoriness: another effect not achieved in full was that of the vertical cleft at each end of the skyscraper, intended to be an unbroken fissure of light. In reality it is segmented by the protruding floor slabs those «confounded little balconies that had to be extended for structural reasons.

Ponti, talking to himself in Domus, lamented the fact. And he was right to do so, for with the passing of time it is only the architecture, the form, that remains, not the reasons behind it. And besides, the more intelligently it complies with them, and the more it is «made to measure the more, as a delicate instrument, it risks falling into disuse. Today, thirty years after their appearance, Milan's two towers, the Pirelli and Velasca buildings, antagonistic in their view of history, both belong to history. They are part of the city's complexity and contradictions I like skyscrapers close to one another. In this sense, and only in this sense, Gio Ponti was thinking of New York. Ponti always loved the skyscrapers of New York, the bristling city as he Corbusier called it, as an American fairy tale. They prompted him to speak more of the sky and the city than of the architecture penetrating into the sky with perfect building machines. Over the silver surfaces the sky will move, with its clouds.According to Ponti himself, it was not New York but his experience of Brazil (1952) that led him to the Pirelli building. In Brazil the Brazil awakened by he Corbusier, it was the encounter with Niemeyer and with his extraordinary formal imagination that helped Ponti to free his own form the results of this would be seen in the projects for Venezuela. There are a thousand different images of the Pirelli tower and its highly popular profile. Ponti always rejected photographs taken from below, which invent a dynamic impetus that the building does not have. Ponti's architecture is one of subtle equilibrium, not impetus. The Pirelli skyscraper was designed by the Studio Ponti Fornaroli Rosselli in collaboration with the Studio Valtolina-Dell'Orto; structural consultants, Arturo Danusso, Pier-Luigi Nervi.