Professor Kleiner discusses the revolution in Roman architecture resulting from the widespread adoption of concrete in the late second and first centuries B.C. She contrasts what she calls innovative Roman architecture with the more traditional buildings already surveyed and documents a shift from the use of concrete for practical purposes to an exploration of its expressive possibilities. The lecture concludes with a discussion of the Sanctuary of Fortuna Primigenia at Palestrina, an impressive terraced complex that uses concrete to transform a mountain into a work of architecture, with ramps and stairs leading from one level to the next and porticoes revealing panoramic views of nature and of man-made architectural forms. Reading assignment: Claridge, Amanda. Rome, pp. 45-47 (building techniques), 47 (exterior finishings), 239-240 (Tabularium), 243-245 (Theater of Marcellus), 368-369 (Porticus Aemilia) Credits: The lectures in HSAR 252 are illustrated with over 1,500 images, many from Professor Kleiner’s personal collection, along with others from a variety of sources, especially Wikimedia Commons, Google Earth, and Yale University Press. Some plans and views have been redrawn for this project. For specific acknowledgments, see: http