The Chicago School refers to two architectural styles derived from the architecture of Chicago. In the history of architecture, the first Chicago School was a school of architects active in Chicago in the late 19th, and at the turn of the 20th century. They were among the first to promote the new technologies of steel-frame construction in commercial buildings, and developed a spatial esthetic which co-evolved with, and then came to influence, parallel developments in European Modernism. Much of its early work is also known as Commercial Style.