Technological improvements continued. Corrugated iron (or galvanized corrugated iron - CGI) was invented in the 1820s by the British Henry Robertson Palmer, architect and engineer of the London Dock Company. Its use spread in rural architecture in the United States and other countries.

Since the 1840s, innovations in the steel industry generalized the use of iron plates, "double T" profiles and higher quality steel at increasingly lower prices (Bessemer converter, 1855). In 1867, Charles Drake of the Patent Concrete Building Company patented the use of iron formwork panels instead of wood.[8]​.

They began to build cast-iron buildings") ("cast iron buildings") especially in SoHo "SoHo (New York)") of New York (E. V. Haughwout Building, John P. Gaynor"),[9]​ 1857), highlighting the constructions of James Bogardus (63 Nassau Street, 1844, 254-260 Canal Street, 1857, 75 Murray Street, 1858, 85 Leonard Street, 1861, Iron Clad Building"),[10]​ 1862). In London, an iron and glass dome 18 meters in diameter had been erected at the Coal Exchange") (James Bunstone Bunning") 1847-1849).

In mid-century Paris, the Saint Genevieve library (by Henri Labrouste, 1843-1850) stood out, in a neo-Renaissance style on the outside but which revealed the metal structure inside. A similar resource was applied in the Museum of Natural History at the University of Oxford, this one in the neo-Gothic style (1855, Henry Acland, with the support of John Ruskin).

The refinement in iron casting ended up gaining its acceptance even as a noble material for making sculptures that until then were reserved for bronze ("Kasli iron")", in the Urals, 1860).

The social acceptance of exposed iron for visible architectural elements had occurred with the extraordinary success of iron and glass architecture from the construction of the spectacular glasshouses of Chatsworth" (Joseph Paxton, 1837-1840), the Palm House of the Royal Botanic Gardens, Kew (architect Decimus Burton and foundryman Richard Turner"), 1841-1849) and, above all, the Crystal Palace of Joseph Paxton (1851), who also demonstrated the possibilities of new materials for prefabricated architecture") (it was assembled, dismantled and reassembled in very short terms, despite its extraordinary dimensions).[11] Similar criteria were applied to the coverage of new types of buildings demanded by economic expansion: shopping galleries, and railway architecture"),[12]​ who built monumental railway stations throughout Europe. Railway engineering built bridges of great daring and beauty, such as that of Théophile Seyrig in Porto (María Pía Bridge, 1877).

By the time of the construction of the Garnier Opera (1861-1875), iron was already being used naturally and profusely in all types of structural elements (especially pillars, beams and plates joined by rivets).

The Chicago fire of 1871 gave rise to massive urban reconstruction, with the first steel frame skyscrapers and new concepts of form and function that characterize the so-called Chicago School (architecture).

The most impressive iron buildings of the century were built by French engineers for the Paris World's Fair of 1889: the Galerie des machines") (Victor Contamin – architects Ferdinand Dutert and Stephen Sauvestre–) and the Tour Eiffel (Alexandre Gustave Eiffel).

The emulation of European and American technical achievements led to a true "iron fever"[13]​ in Latin America,[14]​ especially in the fastest growing cities, such as those of the rubber fever (Iquitos, Manaus). In Mexico "iron palaces" were built in the capital (1888-1891) and in Orizaba (by Eiffel, 1891-1894).

Between the middle of the 19th century and the first third of the 20th century, a notable technical progression developed (with some spectacular catastrophe – collapse of the Tay Bridge"), 1879–) in the construction of iron bridges (Wheeling Suspension Bridge, 1849, Stadlauer Ostbahnbrücke") in Vienna, 1868-1870, Brooklyn Bridge in New York, 1870-1883, Don Luis I Bridge in Porto, 1881-1886, Tower Bridge in London, 1886–1894, Vizcaya Bridge, by Ferdinand Anodin") and Alberto del Palacio, 1887-1893, Vierendeel Bridge in Avelgem, 1896-1902, Manhattan Bridge in New York, 1909, Hercílio Luz Bridge in Florianópolis, 1922-1926, Golden Gate in San Francisco, 1933-1937), which continues to the present day.

In addition to the intrinsic beauty of the structures, urban bridges became a vehicle for artistic expression in their ornaments, especially some bridges in Paris or Saint Petersburg), made in the style of eclectic architecture.

The "cast-iron builders" became a stereotype of the thriving business bourgeoisie of the 19th century who, in the words of Karl Marx, built "wonders far greater than the pyramids of Egypt." Confidence in the idea of ​​progress identified its science and technology with its superiority over the rest of the world (imperialism, "white man's burden"). "Iron" became an attractive epithet to describe characters characterized by their will and strength (Otto von Bismarck, "the iron chancellor" –Eiserne Kanzler–). The economic theory that defended the existence of a natural necessity that wages could never rise above the subsistence level was called the "iron law of wages." At the same time, the labor movement developed through identification with a particular type of "worker", that generated by mining, steel or construction.

Technological improvements continued. Corrugated iron (or galvanized corrugated iron - CGI) was invented in the 1820s by the British Henry Robertson Palmer, architect and engineer of the London Dock Company. Its use spread in rural architecture in the United States and other countries.

Since the 1840s, innovations in the steel industry generalized the use of iron plates, "double T" profiles and higher quality steel at increasingly lower prices (Bessemer converter, 1855). In 1867, Charles Drake of the Patent Concrete Building Company patented the use of iron formwork panels instead of wood.[8]​.

They began to build cast-iron buildings") ("cast iron buildings") especially in SoHo "SoHo (New York)") of New York (E. V. Haughwout Building, John P. Gaynor"),[9]​ 1857), highlighting the constructions of James Bogardus (63 Nassau Street, 1844, 254-260 Canal Street, 1857, 75 Murray Street, 1858, 85 Leonard Street, 1861, Iron Clad Building"),[10]​ 1862). In London, an iron and glass dome 18 meters in diameter had been erected at the Coal Exchange") (James Bunstone Bunning") 1847-1849).

In mid-century Paris, the Saint Genevieve library (by Henri Labrouste, 1843-1850) stood out, in a neo-Renaissance style on the outside but which revealed the metal structure inside. A similar resource was applied in the Museum of Natural History at the University of Oxford, this one in the neo-Gothic style (1855, Henry Acland, with the support of John Ruskin).

The refinement in iron casting ended up gaining its acceptance even as a noble material for making sculptures that until then were reserved for bronze ("Kasli iron")", in the Urals, 1860).

The social acceptance of exposed iron for visible architectural elements had occurred with the extraordinary success of iron and glass architecture from the construction of the spectacular glasshouses of Chatsworth" (Joseph Paxton, 1837-1840), the Palm House of the Royal Botanic Gardens, Kew (architect Decimus Burton and foundryman Richard Turner"), 1841-1849) and, above all, the Crystal Palace of Joseph Paxton (1851), who also demonstrated the possibilities of new materials for prefabricated architecture") (it was assembled, dismantled and reassembled in very short terms, despite its extraordinary dimensions).[11] Similar criteria were applied to the coverage of new types of buildings demanded by economic expansion: shopping galleries, and railway architecture"),[12]​ who built monumental railway stations throughout Europe. Railway engineering built bridges of great daring and beauty, such as that of Théophile Seyrig in Porto (María Pía Bridge, 1877).

By the time of the construction of the Garnier Opera (1861-1875), iron was already being used naturally and profusely in all types of structural elements (especially pillars, beams and plates joined by rivets).

The Chicago fire of 1871 gave rise to massive urban reconstruction, with the first steel frame skyscrapers and new concepts of form and function that characterize the so-called Chicago School (architecture).

The most impressive iron buildings of the century were built by French engineers for the Paris World's Fair of 1889: the Galerie des machines") (Victor Contamin – architects Ferdinand Dutert and Stephen Sauvestre–) and the Tour Eiffel (Alexandre Gustave Eiffel).

The emulation of European and American technical achievements led to a true "iron fever"[13]​ in Latin America,[14]​ especially in the fastest growing cities, such as those of the rubber fever (Iquitos, Manaus). In Mexico "iron palaces" were built in the capital (1888-1891) and in Orizaba (by Eiffel, 1891-1894).

Between the middle of the 19th century and the first third of the 20th century, a notable technical progression developed (with some spectacular catastrophe – collapse of the Tay Bridge"), 1879–) in the construction of iron bridges (Wheeling Suspension Bridge, 1849, Stadlauer Ostbahnbrücke") in Vienna, 1868-1870, Brooklyn Bridge in New York, 1870-1883, Don Luis I Bridge in Porto, 1881-1886, Tower Bridge in London, 1886–1894, Vizcaya Bridge, by Ferdinand Anodin") and Alberto del Palacio, 1887-1893, Vierendeel Bridge in Avelgem, 1896-1902, Manhattan Bridge in New York, 1909, Hercílio Luz Bridge in Florianópolis, 1922-1926, Golden Gate in San Francisco, 1933-1937), which continues to the present day.

In addition to the intrinsic beauty of the structures, urban bridges became a vehicle for artistic expression in their ornaments, especially some bridges in Paris or Saint Petersburg), made in the style of eclectic architecture.

The "cast-iron builders" became a stereotype of the thriving business bourgeoisie of the 19th century who, in the words of Karl Marx, built "wonders far greater than the pyramids of Egypt." Confidence in the idea of ​​progress identified its science and technology with its superiority over the rest of the world (imperialism, "white man's burden"). "Iron" became an attractive epithet to describe characters characterized by their will and strength (Otto von Bismarck, "the iron chancellor" –Eiserne Kanzler–). The economic theory that defended the existence of a natural necessity that wages could never rise above the subsistence level was called the "iron law of wages." At the same time, the labor movement developed through identification with a particular type of "worker", that generated by mining, steel or construction.