The purpose of this thesis is to discuss the stylistic development of the Italian architect Aldo Rossi from Modern to Post-Modern design. A summary of the Modern architectural movement is presented along with an analysis of the developments in Post-Modern architecture since 1960. The influence of Italian culture on Rossi's career is discussed through a brief survey of Ancient Roman archetypal motifs and Italian architecture of the early 20th century. Several key buildings proposed or constructed by Rossi from 1960-1990 are discussed based on his concepts of analogy, typology, morphology and rationalism.