Many metropolitan cities have been faced with sustainability issues at the beginning of the twenty-first century. The problems are related to several subjects. Two of them are essential for the sustainability of townscapes: one is the subject of visual sustainability of the character of a townscape, and the other is the sustainable development of the city and its relation with the urban form. Overcoming the difficulties arising from the improper use of city's resources can be possible by understanding the true nature of its urban form, how urban landscapes have developed historically, and which processes have shaped their forms. Typomorphology is a method for understanding the character of the urban form. It reveals the physical and spatial structure of cities. In this work, typomorphological method will be introduced, and its importance will be discussed according to sustainability of townscapes.