Chicago, 8 October 1871. The Great Fire destroyed almost a third of the city — 18,000 buildings, 100,000 homeless. The reconstruction lasted twenty years and was the largest urban-planning operation of nineteenth-century America. It is in this context — a city rebuilding in haste, with new construction techniques, on compact and expensive land — that the skyscraper was born. Not as an artistic idea but as a response to a problem: how to build the greatest number of square metres on the same plot of land.
The techniques already exist: the steel frame (which replaces load-bearing masonry walls), Elisha Otis's elevator (1852, later perfected), reinforced concrete. The problem is not technical — it is aesthetic. How do you give beautiful form to a building that is essentially a pile of identical floors stacked 10, 15, 20 storeys high? The first Chicago skyscrapers of the 1870s–1880s are ugly precisely because they do not solve this problem: they clad the steel structure with eclectic façades — neo-Gothic, neoclassical — that have nothing to do with the underlying structure.
Sullivan's solution
Louis Sullivan — born in Boston in 1856, trained in Paris at the École des Beaux-Arts, moved to Chicago in 1873 — solved the problem with the Wainwright Building in St. Louis (1891) and then with the Guaranty Building in Buffalo (1895). The solution is this: divide the building into three vertical parts, like a classical column. The ground floor and second floor (the base) are treated with heavy materials, pierced by large commercial windows. The intermediate floors (the shaft) have a continuous vertical texture — a grid of slender piers expressing the underlying steel structure. The top floor (the capital) is treated with an ornamental cornice that closes the building vertically.
And here we must be precise: Sullivan does not invent simplicity — he invents a system of three vertical elements that gives visual sense to height. His ornament — extremely rich, organic, naturalistic — is not decoration applied to the structure: it is an integral part of the architecture. Sullivan's ornament is like the foliage of a plant — it is born of the structure and expresses its vitality. For Sullivan nature is the model: a building must grow like a plant, with each part expressing its own function.
The Chicago School and the technical context
Sullivan does not work alone. The “Chicago School” of the 1880s–1900s is a group of architects and engineers who face the same problem — how to build tall in a rebuilding city on clay soils that cannot support deep foundations — and solve it with new techniques. William Le Baron Jenney built the Home Insurance Building in 1885: the first tall building with a load-bearing metal frame (cast and wrought iron, with the first steel beams on the upper floors). John Wellborn Root and Daniel Burnham developed concrete raft foundations for the yielding ground. Adler — Sullivan's partner — solved the acoustic and mechanical problems. Sullivan designed the façades.
The Sullivan–Adler partnership (1883–1895) produced some of the most important buildings of the Chicago School. The Auditorium Building (1889) — 17 floors, a 4,200-seat theatre, hotel, offices — is an extraordinary multifunctional machine for its time. Adler solved the acoustics (the theatre is still among the best-sounding in the world) and Sullivan designed the interiors: a system of gold-painted cast-iron ornament, with round arches, columns, plant capitals. It is not minimalism — it is organic maximalism. Ornament is the program, not the decoration.
“Form follows function” — the most famous misunderstanding
Sullivan's most famous phrase — “form ever follows function” — was interpreted by the Modern Movement as a manifesto of austere functionalism: buildings must be free of ornament, must express function directly and nakedly. It is exactly the opposite of what Sullivan meant. For Sullivan “function” includes the spiritual and poetic dimension of architecture — not only technical efficiency. Nature is his model: an oak leaf has “form that follows function”, but it is not free of ornament. The oak is not minimalist.
Sullivan died in 1924 in poverty — abandoned by clients after the 1893 Columbian Exposition in Chicago, which had brought neoclassical architecture back into fashion. His pupil Frank Lloyd Wright would build another American architecture — organic, rooted in the landscape — that has little to do with the skyscraper but everything to do with Sullivan's teaching on the relationship between form, function and nature. And Wright would be the only one to remember Sullivan at his death, in squalor, in a Chicago hotel. “The master” — that is what he called him.