If Miesian modernism had made steel elegant and quiet, the high-tech movement of the '70s and '80s makes it loud, colorful, unabashedly on display. It isn't a simple evolution of style: it's a shift in philosophy about the relationship between structure and representation, and its protagonists — Renzo Piano, Richard Rogers, Norman Foster — share training and job sites but develop three distinct ways of making steel the protagonist.
Where high-tech came from
The movement did not come out of nowhere. In 1963 Norman Foster and Richard Rogers, just back from Yale, founded the practice Team 4 in London with Wendy Cheesman and Su Brumwell. Their last building together, the Reliance Controls factory in Swindon (1967), was already a manifesto: a shed with an exposed steel frame, diagonal bracing on the façade and a single large open space where offices and production coexisted without partitions. In the background were the visionary images of Archigram, with their cities made of components plugged in and removed by cranes, and above all Cedric Price's Fun Palace (1961), never built: a huge metal frame inside which platforms, ramps and movable walls were to reorganise themselves continuously according to the activities. The Pompidou, ten years later, is in large part the Fun Palace actually built.
The shared idea is that a building should not be a finished object but an infrastructure capable of change. The structure and services are the stable part; everything else must be able to be reorganised. Steel is the ideal material for this idea: it is made in a factory, assembled with bolts, and can be taken apart and replaced piece by piece. Showing it, in this logic, is not merely an aesthetic choice: it means declaring how the building is made and how it can be modified.
Centre Pompidou: structure as spectacle, not something to be shy about
Paris's Centre Pompidou (1977), designed jointly by Renzo Piano and Richard Rogers with engineer Peter Rice, overturns every previous convention: not only does the steel structure stay exposed, it's pushed entirely outside the envelope, along with all the building services (air ducts painted blue, plumbing in green, electrical routes in yellow, vertical circulation in red). The interior becomes a totally free plan, with no columns or ducting in the way of the exhibition space — the entire technical and structural apparatus has been turned literally inside out onto the façade. It's a move that owes a great deal to industrial color-coding (pipes colored by function were already standard practice in petrochemical plants) applied for the first time to a public building of cultural significance, with an effect that still divides opinion today: machine or museum, refinery or temple of culture.
Lloyd's of London: Rogers's exoskeleton
Richard Rogers takes the same logic to an even more radical level in the Lloyd's of London building (1986): here the services (stairs, elevators, restrooms, ventilation ducts) are gathered into six towers clad in stainless steel and pushed to the building's outer perimeter, and the load-bearing columns also stand outside the glazed façade. They are concrete: the original design was in steel, but a reinforced concrete frame was chosen to meet fire regulations. The whole arrangement leaves the interior space completely free and flexible — a functional choice as much as an aesthetic one: a financial office building, whose internal layout keeps changing over time to suit the shifting needs of market operators, gains enormously from an interior core free of fixed constraints.
Lloyd's won critical recognition very quickly: in 2011, just twenty-five years after completion, it was listed at the highest level of English heritage protection, Grade I, becoming the youngest building ever to achieve it. The recognition, however, raised a new problem. A building designed to change, with services meant to be replaced, becomes a monument to be preserved: any work on the external elements, even those conceived as temporary, now requires the care reserved for historic assets. It is a paradox that affects much high-tech architecture, and it shows how the idea of flexibility clashes with the value society places on a building's image.
Norman Foster: transparency as method, not just effect
Norman Foster develops a more controlled, less exhibitionist approach, but one no less radical in its use of steel: the HSBC building in Hong Kong (1985) is built around eight structural steel towers prefabricated in Britain and assembled on site as industrial components — a method that drastically cuts construction time in an extremely dense urban context. Perhaps the most instructive project for understanding the technical evolution of the high-tech language, though, is London's Swiss Re Tower (2004, known as "the Gherkin"): its diagrid structure — a diagonal mesh that replaces both vertical columns and horizontal beams with a single inclined lattice system — cuts the amount of steel needed by about 20% compared with a conventional frame at equal performance, because every member of the mesh works in both axial compression/tension and contributes to the whole building's torsional stiffness, instead of specializing columns and beams into separate roles as in the classic frame.
Foster also shows that the high-tech language can reverse the Pompidou's lesson. At the Stansted Airport terminal north of London (1991), the services are neither on the roof nor on the façade but in a basement service level beneath the passenger floor. The roof thus becomes extremely light, a lattice of shallow domes carried on steel structural trees that also bring daylight into the centre of the great hall. The result is an airport where you find your way by looking at the sky, and the structure, instead of displaying the services, is reduced to the essentials. In the Gherkin, too, the structure has a climatic task: between floors, openings rotated in a spiral create multi-storey atria that encourage natural ventilation and bring light deep inside, and the rounded shape reduces wind eddies at the foot of the tower.
The engineer as co-author
A trait common to the entire high-tech era, often overlooked in narratives centered solely on the architects, is the co-authorship role of structural engineers like Peter Rice (Ove Arup & Partners), who worked with Piano and Rogers on the Pompidou and then with both on many later projects, or Anthony Hunt, the engineer of Foster's early buildings. The apparent lightness of these structures doesn't come from a purely formal intuition, but from structural calculation pushed to the limits of the codes of the time — truss systems optimized joint by joint, cast-steel rocker brackets (the Pompidou's famous "gerberettes") designed specifically for that building and no other. High-tech aesthetics, in this sense, doesn't simplify engineering to make it spectacular: it puts it on display precisely because, upstream, it's already engineering work of extremely high precision.
Two examples show how much engineering shaped these buildings. In the HSBC headquarters in Hong Kong, designed with Arup's engineers, the floors do not rest on columns spread across the plan: they hang from large two-storey-high trusses, placed at intervals up the height of the tower and carried by the eight composite masts. In this way the ground floor remains a covered public plaza crossed by pedestrians, and an atrium about ten storeys high opens at the centre of the building. To bring daylight to the bottom of the atrium, an array of adjustable mirrors, the "sunscoop", is mounted on the outside of the building; it tracks the sun and reflects light inwards through a mirrored ceiling. The structure is therefore not only load-bearing: it organises the city at the building's foot and the light at its heart.
The second example is the Kansai Airport terminal in Japan (1994), designed by Renzo Piano with Peter Rice. The building, about 1.7 kilometres long, stands on an artificial island built in Osaka Bay, in an area prone to earthquakes and typhoons, on ground destined to sink for years under its own weight. The curved steel roof has a shape derived from the movement of air inside the hall, which is blown in from one side and flows along the ceiling without the need for enclosed ducts. To deal with ground settlement, devices were provided at the base of the columns to adjust their height as the island settles unevenly. It is perhaps the clearest example of how, in these buildings, form is the visible consequence of a technical problem solved.
The price of exposed steel
Exposing steel has technical costs that designers need to know. The first is corrosion. An external structure is exposed to rain, condensation and pollution, and must be protected with paint systems chosen according to how aggressive the environment is: the ISO 12944 standard classifies environments into increasing corrosivity categories, from dry interiors to marine and industrial settings, and for each it sets out protection systems and expected lifetimes. An exposed structure must then be inspected and repainted periodically, and joint details must avoid standing water and inaccessible areas. The second cost is fire. Steel does not burn, but at temperatures of around 500–600 °C it loses much of its strength; to keep it visible, intumescent paints are used, which swell with heat to form an insulating layer, or sections are oversized. These choices affect costs and, in the most slender structures, can change their appearance.
The Centre Pompidou is the most visible case of these costs over time. After less than twenty years of use it already needed a major restoration campaign, completed in 2000, and in 2025 it closed again for a multi-year project, with reopening planned for 2030, devoted among other things to asbestos removal, energy efficiency and accessibility. A building that shows everything ages in front of everyone: maintenance is not an exception but part of the design from the outset.
After high-tech
The practices of the three protagonists continued to use steel expressively, but with changed aims. London's Leadenhall Building (2014), designed by Rogers's practice, has a large exposed steel megaframe with diagonal bracing, which carries the building and leaves the floors free of internal columns. The Millau Viaduct in France (2004), designed by Foster with the engineer Michel Virlogeux, has a steel deck about 2.5 kilometres long, carried by stays and very tall piers. Renzo Piano, for his part, brought the same constructional precision to other materials, from timber to terracotta to glass. The most lasting legacy of high-tech is therefore not an aesthetic but a way of working: designing with the engineer and with industry, thinking of the building as an assembly of components, and making legible how it is made.