I set foot in Chicago for the first time thinking I was going to see skyscrapers. I found something more interesting: the question that comes before skyscrapers. Why here? Why now — that is, why in the 1880s, not before, not elsewhere? The fire of 1871, which destroyed almost a third of the city, created the conditions: an urban centre to be rebuilt in a hurry, real-estate speculators with capital to invest, and — for the first time in history — a structural material cheap enough to build tall. Industrial rolled steel. Before, it did not exist in the necessary quantities. From 1880 on, it did.
Chicago is the laboratory where people discovered how to build vertically. Not in the sense that engineers had the solution and applied it — in the sense that every building was an experiment, and every experiment solved a problem the previous one had left open. This itinerary does not follow heights. It follows discoveries.
Rookery Building — the first with a mixed structure
The Rookery dates from 1888, designed by Burnham and Root — Daniel Burnham, who would become the city's grand planner, and John Root, the theorist of structure, who died young and is often forgotten. The problem the Rookery solves is a fundamental one: how do you build a tall building without Chicago's ground — unstable lake clay — giving way under the weight?
The answer is the raft foundation — a grid of interlocked steel beams, with concrete footings, that spreads the load over a far wider area than traditional point foundations. It is the solution that made it possible to build tall on this type of soil, and it was not found in books — it was tested here, on these buildings, with these engineers.
The structure is mixed: load-bearing masonry walls on the outer façades, a metal frame inside and around the light court. The interior atrium — modified by Frank Lloyd Wright in 1905 — is one of the most beautiful interior spaces in Chicago: a court covered by an iron and glass structure, with decorated cast-iron balconies rising to the upper floors. Wright kept the structure and changed the details. It is one of the few cases in which a renovation improved the original.
Auditorium Building — Adler and Sullivan
The Auditorium Building of 1889 is the project that made Louis Sullivan known — the theorist of the skyscraper, the man who formulated the phrase “form follows function” — but it is also the project in which Dankmar Adler, the engineer, solved an acoustic problem that seemed impossible.
The internal concert hall — 4,200 seats — was in 1889 the largest hall in the United States, and had to have acoustics that worked both empty and full, both for opera and for political rallies (party conventions were held here). Adler studied the problem systematically, empirically observing how sound behaved in existing halls (Sabine's reverberation theory would only come a few years later), calibrating the ceiling arches of the hall to diffuse sound evenly. The result is still considered one of the best acoustic interiors of the nineteenth century.
Sullivan designed the ornamentation — a system of plant decorations, in cast iron and gilded terracotta, covering arches, capitals, surfaces. It is not applied decoration: for Sullivan it is the demonstration that structure and ornament are not in conflict. Ornament is the way in which structure declares its own character.
Sullivan's thought and the origins of the skyscraper: Sullivan and the Chicago School.
Chicago Architecture Walking Tour — the Chicago School
The Chicago Architecture Center runs boat tours on the Chicago River that pass under and beside the historic buildings — it is one of the best ways to see the city, because many of the most important façades face the river. But to understand the Chicago School you need to walk in the Loop: the network of streets and elevated tracks around the centre is scattered with buildings that tell the structural evolution of the years 1880–1920.
The Monadnock Building of 1891–1893 is the tallest building in the world with load-bearing masonry walls — the walls at ground level are 1.8 metres thick to carry the sixteen floors above. It is the physical limit of masonry construction: you cannot go higher with this system without the walls taking up all the interior space. The metal skyscraper was born of this practical limit.
The Reliance Building of 1895 — Burnham and Root — is the opposite: a metal frame entirely clad in glass and white glazed terracotta. There are no more load-bearing walls. The façade is a light skin on a steel structure. It is one of the first examples of a curtain wall in history — a façade that does not carry but clads.
Millennium Park — Crown Fountain and Cloud Gate
Millennium Park opened in 2004, on an area that for a century had been a car park and a railway yard on Lake Michigan. It is not architecture in the strict sense — it is urban public space, designed with contributions from different artists. But it is worth spending time in, because it is one of the most successful urban parks of the last thirty years.
Jaume Plensa's Crown Fountain is two glass towers 15 metres high that project videos of the faces of Chicago citizens. Every so often the mouth of the projected face opens and spouts water toward visitors. In summer, children play in it. It is a public artwork that works as a play space — the boundary between art, architecture and park is deliberately vague. Anish Kapoor's Cloud Gate — the polished-steel “bean” — reflects the skyline and people in a distorted way. It is not decorative: it produces an effect that changes with the angle, the hour, the season. They are two works that make space, city and people talk to each other.
875 N Michigan Ave — the grid seen from above
The John Hancock Center — today 875 N Michigan — dates from 1969, designed by SOM (Skidmore, Owings and Merrill). The most recognisable visual element is the steel X-bracing that crosses the façade diagonally: it is not ornament, it is the structure. The diagonal braces resist the lateral wind that at a hundred floors produces enormous forces. SOM brought the structure to the façade because it is the most efficient place to put it — and the result is a skyscraper that does not try to hide how it works.
From the Hancock's observation deck, the most useful thing you can do is not to look at the lakes or the horizon: it is to look down. Chicago's street grid — drawn in 1830, unchanged in its logic — is visible from above in a crystal-clear way. A mile by a mile, the main streets every eight blocks, the 100-metre block, the alignment to the lake. It is Cartesian urbanism applied on a metropolitan scale, and from above you understand why Chicago is so easy to navigate: the system is legible.
Frank Lloyd Wright and his Chicago root: Frank Lloyd Wright — the Prairie House and open space.
What you have understood
Chicago is not a beautiful city in the European sense — it does not have the historical compression of Rome or the scenography of Venice. It has something different: it has the clarity of a city built by people who knew exactly what they were trying to do. Every historic building in the Loop solves a problem that the previous one had opened. The sequence has a logic — almost scientific — that can be read only if you walk in the right order.
The Chicago School was not a school in the academic sense: it was a group of engineers and architects working in the same city, in the same decade, on similar problems. They copied each other, cited each other, improved one another. Nobody invented the skyscraper: it emerged from a collective, iterative, experimental process. Like all true inventions.