This lecture discusses the importance of public spaces in urban centers, focusing on the transformation of the central pedestrian area in Brussels and the broader implications for urban planning, social cohesion, and environmental sustainability. The speaker emphasizes the need for redefining city centers to enhance their attractiveness, promote social cohesion, and prioritize pedestrian-friendly environments. The lecture also addresses the challenges and opportunities related to urban mobility, social diversity, and the temporal management of public spaces, highlighting the complex interplay between urban design, community engagement, and policy-making.