Since the 1960s, tourism has had a profound impact on cities. Many great cities, such as Paris or Rome, are discovering that their historic centers are becoming tourist ghettos abandoned by local residents. At the same time, new towns have been specially created to welcome tourists. The subject of the lecture is the history of cities and architecture in the perspective provided by the questions of leisure and tourism. These two practices, reserved to an elite minority until the nineteenth century, have spread largely. Today, they concern a large majority of the people in Western countries. The lecture will be structured according to a thematic approach: seaside and winter resorts, shopping as a form of leisure, Olympic cities, theme parks. . . . Some lectures will concern a particular period. The study of the \'Folies\' and \'Tivolis\' will deal for instance with eighteenth-century London and Paris. Each student will be required to choose a case study and make a presentation during the second part of the meeting. A final paper on the same subject will be required for the end of the semester.