Final answer:
Louis Sullivan is known as the father of modern architecture because he introduced the principle of 'form follows function,' which became a cornerstone of modern design, and he was instrumental in the creation of the skyscraper.
Step-by-step explanation:
Louis Sullivan is considered the father of modern architecture due to his pioneering role in the development of the skyscraper and his famous dictum, "form follows function." This concept emphasized that architectural design should prioritize the purpose and function of a building over the ornamentation, advocating for a visual expression of structure and the use of industrially produced materials, such as iron, steel, and glass. His ideas spurred a revolution in the design and aesthetic of buildings and laid the foundation for modernist architecture. Moreover, Sullivan's influence extended to his students, most notably Frank Lloyd Wright, who carried Sullivan's principles forward and adapted them into his own philosophy of organic architecture. Together, Sullivan and his proteges like Wright facilitated a transition from traditional architectural styles to what would become known as modern architecture, shaping the skylines of cities and the parameters of architectural thought.