Today's lecture is about the history of urban planning. One key figure is Baron Haussmann, who redesigned Paris in the 1850s. His main goals were to improve traffic flow, create open spaces, and reduce the risk of disease by widening streets. However, a less obvious effect was that the new wide boulevards made it harder for citizens to build barricades during revolts. This was seen as a way to maintain public order, but it also changed the social character of the city, displacing many working-class residents to the outskirts.