The dynamics of globalization brought a radical change in megacities and tensions between the stakeholders and dwellers against top-down urban renewal policies. This unique book provides a worldview of multi-stakeholders in the urban housing market. With a longitudinal research approach, it paves the way for interdisciplinary researchers to critically assess the urban renewal projects and update such studies. The urban renewal processes are implemented without participation, and the book highlights field-based information for policymakers. The reader will find, with the information provided from the field, why participation is necessary for a sustainable urban development, why there are different types of urbanizations, and how it works under different conditions. Better understanding of the challenges of urban renewal processes in the world cities is intended with the focus on the changing informal settlements. Istanbul is a megacity, housing more than half of its dwellers in informal settlements. After many decades of self-upgrading and silently communicating with the local authorities, the informal sector had become adapted and maintained its living spaces. Unexpectedly, the end of the first decade of the 21st century marked a radical urban land valuation and international investments. Top-down interventions started with naming Istanbul the 2010 European Capital of Culture. Then came the Law of Urban Transformation, which meant the fast decline of squatter housing and the speedy loss of its cultural value of the mahalle spirit, place identity. The book will raise curiosity on why the time has come to change the perspectives about the informal urban sector.