Some prestigious urban projects demonstrate many forms of misfit, misfortune, or mismanagement. Without big plans and high ambitions large projects don’t get off the ground, however, with a lack of attention for a diligent implementation and organization, fiascoes will follow. In the city of Rotterdam, the realization of a pop music hall, failed completely. In this case, the municipal public real estate agency played a central role in the failure of this urban project, and even a huge fraud that wasted millions of euros came out in the open. The main question in this article is: what can we learn from projects that fail during the implementation phase, and how can we professionalize public real estate agencies to avoid mistakes, fraud and other fiascoes? Such questions are relevant for public agencies that have to deal with both high and ever changing political and managerial ambitions, as well as with several commercial actors. This article offers insights behind the scenes of a public real estate agency, based on an in-depth case study. The authors demonstrate mechanisms of organizational vulnerability during the implementation of urban projects, as well as critical success factors of a professional, mature public real estate agency.@en