Which architectural innovation is associated with the development of skyscrapers at the end of the 19th century?

Structural steel

The introduction of structural steel at the end of the 19th century revolutionized architecture, enabling the creation of the first skyscrapers. Before this innovation, buildings were limited in height by the capacity of load-bearing walls made of stone or brick to support weight. Steel, with its exceptional strength and ability to support heavy loads over large spans, opened new possibilities in terms of height and architectural design. The Home Insurance Building in Chicago, completed in 1885, is often cited as the world's first skyscraper, marking the beginning of the vertical era in urban architecture. This advancement not only transformed city skylines around the world but also changed the way we live and work, bringing people together in vertical spaces.