Groun­ding Height

Testo in italiano al seguente link 

In 1885, with the completion of William Le Baron Jenney’s Home Insurance Building, Chicago welcomed one of the buildings that would come to mark the birth of the modern skyscraper. Only a few years later, the same city set a height limit of just under 40 metres for buildings in its centre: having set the race upwards in motion, it already felt the need to regulate it. Yet the contest for the sky is far older. In medieval Italian cities, the tower was a fortified residence, a stronghold and a visible measure of a family’s power. San Gimignano once counted around seventy of them, so many that in 1255 the municipality ruled that no private tower could rise above the public one, the Torre Rognosa. Six centuries later, across the Atlantic, the question remained essentially unchanged. How far can private interest rise vertically before the city feels the need to set a limit?

At the beginning of the twentieth century, Henry James regarded New York’s skyscrapers with suspicion. They were «extravagant pins in a cushion already overplanted», driven in «anywhere and anyhow», «giants of the mere market»: verticality as an expression of land value and speculation. A decade earlier, Louis Sullivan had made the opposite case for the nature of the new type: «It must be tall, every inch of it tall». Between these two positions lies the central question that has accompanied the skyscraper ever since: the problem is not height in itself, but what it produces in the city. When Simone de Beauvoir arrived in Chicago in 1947, she recognised something different from New York. She admired the hard lines of its skyscrapers, «plus massifs» and «plus purs» than those of New York. Yet Chicago remained, in her eyes, «une ville de pleine terre»: a vertical city that did not seem to have severed its ties with the ground, the street and the life at its feet.

Perhaps it is precisely at ground level that the tall building faces its hardest test. From a distance it belongs to the skyline; up close, to the street. Its uppermost metres can be exceptional, abstract, even indifferent to their surroundings; the first twenty cannot. Here it meets pavements, entrances, shops, trees, people waiting and crossing. Here the concentration of floor area and people must be transformed into urban intensity. Jane Jacobs had grasped this in 1958 when, arguing against complexes that erased the street in favour of generic open space, she pointed to Rockefeller Center – not without a few barbed observations – as the opposite example: «It respects the street» and «knits tightly into every street that intersects it». Its strength lies in introducing pedestrian streets, squares, shops and passages, making the base an urban system rather than merely a podium.

Mies van der Rohe’s Seagram Building addresses the same problem in almost the opposite way. It does not extend the street into the building; instead, it sets the tower back and returns an extraordinarily valuable part of the plot to the city in the form of a void. The plaza is not simply open space: steps, low walls, fountains and a threshold carefully calibrated to the pavement make it inhabitable. William H. Whyte would make it a case study in his research on public space. Yet those same studies would also reveal the other side of the equation: many plazas produced by zoning incentives – windswept expanses with nowhere to sit and no ­reason to linger – remained empty. Void alone does not make a city; it can produce its absence. It is the threshold, more than the setback, that makes the difference.

In São Paulo, Oscar Niemeyer takes yet another route with the Copan. The great sinuous slab, so autonomous on the skyline, loses that same autonomy at ground level: the shopping arcade passes through the base, follows the slope of the site and opens onto the street through five entrances. The continuity of the paving makes it difficult to tell where pavement ends and building begins. Niemeyer does not place the city in front of the tower; he allows it to enter. The building’s contact with the ground thereby acquires depth and becomes fabric. Rem Koolhaas would later identify a «Culture of Congestion» in New York’s delirium, reading the skyscraper as a machine capable of stacking different programmes and worlds. But if that stacking is to become city rather than mere volume, it must be able to touch the ground.

This capacity for concentration brings us back to the question with which we began: does inhabiting height make sense if the tower is reduced to a property-development experiment, driven more by the market than by planning, or can that same concentration give something back to the city that makes it possible? Reflecting with Jonathan Sergison on Zurich’s growth, Tom Avermaete shifts attention from height to relationships. Towers should be judged in relation to place, context and the mix of uses; intermediate typologies work when they accommodate more inhabitants while maintaining a clear connection to the street. Built density and urban density are not the same thing. A tower can concentrate thousands of square metres and produce very little city at ground level; a lower building can produce a great deal through doors, activities, passages and shared spaces.

Perhaps, then, we are still looking at tall buildings from the wrong end. We measure their height, slenderness and effect on the skyline, when a decisive part of their quality is determined much lower down: in the street they make, the uses they accommodate, the relationships they enable, the city they manage to generate around them. Milan, too, for decades entrusted its vertical limit to a single height: no building was supposed to exceed the 108.5 metres of the Madonnina. When first the Torre Breda and then the Pirelli rose beyond that threshold, the city even found a way to sidestep the problem symbolically, placing a replica of the Madonnina on top of Gio Ponti’s skyscraper. The limit could be shifted, the primacy preserved. Now that this measure belongs to the past, a harder question remains: what ­happens when all that height comes back down to earth? The sky has always been negotiable. The ground much less so. For a tower truly belongs to a city when, even before it conquers its sky, it manages to build its ground.