As a response to overcrowding residents of medieval cities built what?

As a response to overcrowding, residents of medieval cities often built taller buildings to maximize limited space, creating multi-story structures that accommodated more inhabitants. They also constructed walls and fortifications to manage urban boundaries and protect against invasions, while some cities expanded outward into nearby areas. Additionally, the development of suburbs and the establishment of markets outside city walls helped alleviate congestion within the urban centers.