To this day large parts of Vienna's urban periphery are shaped by once informal settlements. During the "hungry years" in and after WWI, extreme hardship gave spontaneous rise to several waves of "Bretteldörfer". Half way between shantytowns and allotment gardens, these mostly illegal entities were not only a home to thousands of urbanites but a challenge to state institutions and municipal planning instruments. This layer of the city’s development, significant in terms of both social history and urban planning, has not been explored comprehensively so far. Indeed, it has hardly ever been addressed scientifically. Following another wave of informal settlements in and after WWII, it was the decades following 1945 during which extensive formalisation and infrastructural upgrade took place. Dubbed "legal consolidation", this process kept Vienna’s city administration busy until the 1990s and beyond. The project explores the phenomenon’s spatial and morphological dimensions as well as its impact on planning discourse and public perceptions. It is therefore not least an important contribution to the on-going debate on "hands-on urbanism".