This document summarizes the history and evolution of urban design theory from the late 19th century to present. It discusses how concepts of the city shifted from being viewed as "art" to a "machine" to a "text". Key figures and their theories are outlined for each period, such as Sitte's view of the city as art, Le Corbusier's machine city concepts, and Jacobs critique of modernist planning. The document also discusses the rise of urban design as a discipline in Australia in the 1980s/90s and references several influential urban design texts from that era.