A brief history of the curtain wall, from the Bauhaus to the glass city

Stripping material away from perimeter walls, emptying them of structural duty, conquering transparency: this was one of modern architecture’s founding gestures, arguably its most recognizable language.
The curtain wall – non-load-bearing, continuous glass skin – quickly became the visual shorthand for modern architecture. More than Le Corbusier’s points, such as the ribbon windows or pilotis, it is what most people picture when asked to give modernism a face.

The story of the glass building has always unfolded across two planes: technical and symbolic. Just think of the Glasarchitektur imagined by the German writer Paul Scheerbart – “an architecture of glass that allows the light of the sun, the glow of the moon and the stars to enter rooms not merely through a few windows, but directly through the walls themselves, ideally in great number” – and of the pavilion that Bruno Taut built for the 1914 Werkbund Exhibition in Cologne, which seems to give Scheerbart’s words a fully realized, tangible form. Its crowning dome – no longer masonry, but a system of modular glass elements set within reinforced concrete ribs – stands as a manifesto for that mysticism of transparency. And yet, from that moment on, the paths branching out from it would be many.

From there, paths diverged. Taut’s work would anticipate glass-brick architecture, while the curtain wall’s destiny would expand at the scale of the metropolis and the large building, on a way iconization.
By the late 19th century, the Chicago School had already redefined the language of urban mass through metal structures clad in masonry. Buildings like William LeBaron Jenney’s Home Insurance Building (1885) and Burnham and Root’s Reliance Building (1895) foreshadowed the fully glazed façades that would dominate after World War II. In the meantime, visions remained largely speculative. From 1919 onward, Ludwig Mies van der Rohe imagined a glass tower on Berlin’s Friedrichstrasse – a concept of structure and skin as separate entities, evolving from prismatic to more curved outlines, that was never built, but set the stage.

Industry, meanwhile, was already advancing the cause. Innovations developed for greenhouses – think of the Crystal Palace – began to migrate into architecture. The Fagus Factory (1911) by Walter Gropius and Adolf Meyer, despite being framed by a masonry-and-wood structure, redefined industrial building with corners dissolving into glass, façades projecting outward, and transparency becoming the dominant theme.
Then came the home for a place of experimentation at the intersection of art, craftmanship and industry, the Bauhaus in Dessau (1925), where Gropius turned the curtain wall into an icon. The workshop wing’s full-height glazed façade, detached from the structure, became a defining image of modern movement, one that would inspire works across Europe, including the Olivetti factories in Ivrea, Italy, developed across World War II by Figini and Pollini.

It was only after World War II that the curtain wall truly accessed the scale of reality, then the scale of cities, and finally the global scale. The glass tower became the symbol of modernity, aligned with what MoMA had canonized as the International Style in a landmark 1932 exhibition, and Mies would glorify in the following years. But he would not be alone. Following early experiments in radical transparency – such as the Equitable Building completed in 1948 in Portland, Oregon by Pietro Belluschi – a true epicenter of vertical construction underwent a sweeping transformation: New York, and Midtown Manhattan in particular. It is here, at the turn of the 1950s, that the archetype, the namesake itself, would come into being: the United Nations Secretariat Building, the “Glass House”. Designed under the direction of Wallace K. Harrison, with architects including Le Corbusier and Oscar Niemeyer, the complex presents to the East River a slab over 150 meters tall, where blue-green glass fuses city and landscape into a symbolic statement of a new transparency.

In its wake, curtain walls spread across Manhattan at a dizzying pace. From Lever House by Gordon Bunshaft (SOM), which in 1952 introduced to Park Avenue a fully sealed façade – part of a precisely engineered environmental machine where clear and green glass calibrate light and heat, requiring external systems for cleaning – to its counterpart, the Seagram Building, Mies’s undisputed masterpiece. Here, the solemnity of bronze-tinted glass and the rigor of its geometric order define the composition: interior blinds are fixed in just three positions (open, closed, half) to preserve its clarity, while verticality is emphasized through full-height bronze mullions applied externally, the building’s unmistakable signature. As the curtain wall becomes a globally replicated standard, often producing a kind of architectural anonymity, it simultaneously asserts itself as a poetic device on an equally global scale. One need only look to Milan, where the façade of the Pirelli Tower – immortalized by Italian director Michelangelo Antonioni in La Notte as an emblem of the city’s transformation – stands in Piazza Duca d’Aosta as a built expression of one of its architect Gio Ponti’s most resonant statements: “L’architettura è un cristallo” (Architecture is a crystal).

From the 1970s onward, as grand ideologies, and with them the driving impulses of modernism, began to dissipate, modern architecture revealed its limits, fragmenting into multiple strands: self-irony and critique, aestheticization, and an increasingly sophisticated exploration of technology as a guarantor of human comfort and environmental quality.
The latter two find emblematic expression in the Willis Faber & Dumas building by Foster Associates in Ipswich (1970–75) – a high-tech icon that quite literally lives two lives: a reflective black monolith by day, and at night a luminous, dematerialized structure stripped of its skin, enclosing a carefully calibrated internal ecosystem – and in the Institut du Monde Arabe in Paris, completed in 1987 by Jean Nouvel and Architecturestudio. Here, glass alone no longer mediates between inside and out; instead, a complex system of photosensitive aluminum diaphragms, capable of variable aperture, overlays the curtain wall. These introduce new layers both in building philosophy – the notion of the “double skin” – and in meaning: the diaphragms reinterpret the traditional moucharabieh as a technological device, born of the interplay between technique and culture in search of an “Arab” identity for the building.

Postmodern irony, for its part, spares none of modernism’s certainties, not even the curtain wall. One need only look at Stuttgart, at James Stirling’s Neue Staatsgalerie (1984), where it is distorted into broken, curving ribbons, embedded within monumental terraces of pink stone, its green metal frames set against an exuberant composition of blue and fuchsia pipes.
What began as a manifesto consolidates into the everyday currency of a language, absorbing a multiplicity of nuances and interpretations. The arrival of the third millennium narrates this shift through its most iconic works. It is impossible not to mention the point at which the long trajectories of the curtain wall and glass block intersect: the Maison Hermès by Renzo Piano Building Workshop in Tokyo (1998–2006). From there, then, the focus moves almost immediately to a vast landscape of increasingly complex engineering of the glass envelope, now the very grammar of contemporary architecture.

In 2004, London’s skyline was radically reshaped when Norman Foster’s fuse for 30 St Mary Axe – the “Gherkin” – introduced to the City a structural grid of rhomboid meshes that coincides with the outer envelope itself. Fully glazed in curved and triangular elements, it might somehow echo that German pavilion dedicated to Scheerbart with which this story began. Less than a decade later, in Beijing, OMA completed the CCTV Tower, defined by its dramatic cantilevered loop, and clad in a glass-and-steel diagrid. Here, the density of the structural lattice thickens to register zones of greater or lesser stress, making performance legible on the façade. By now, the curtain wall has become a field of experimentation that extends well beyond its symbolic origins. The Shard – London Bridge Tower, once again by Renzo Piano Building Workshop – makes this clear: its concept is rooted in fragmentation, a volume defined by eight double-skin glass façades, each tilted by about six degrees, never quite touching, their differing orientations modulating solar gain and outward reflections.

Above all, however, the curtain wall has become a linguistic – post-ideological, one might say – device. It wraps and defines the myths of contemporary progress, from the race for the world’s tallest skyscraper – still led by the Burj Khalifa in Dubai, yet another SOM project, whose 828 meters of glass are engineered to perform under extreme desert conditions of thermal variation, wind, and downdrafts generated by its own height – to works of the most rarefied refinement.
Among these, the mirrored, almost otherworldly ring with which OFFICE KGDVS linked two buildings of the Belgian Federal Parliament in Brussels – the Tondo, completed in 2020 – seems to dematerialize the massive structure required to suspend a curved passage between different elevations, at times appearing instead almost mineral, dense and solid, depending on the sky it reflects. “Not just windows, but walls themselves, ideally in great number”. More than a century after Glasarchitektur, and after Mies’s crystal towers, the glass city has shifted from manifesto to condition, revealing how readily we continue to invest the conquest of transparency with ever-new meanings.

Opening image: Photograph by Gili Merin, Courtesy of OMA