Once upon a time, there was a building in the heart of the city, an architectural gem at the center of the concerns of elected officials and citizens, now demolished, replaced by a luxury apartment building, currently under construction, the new fruit of the architectural work of men. This is the story of the Palais des Congrès in Rouen, once standing on the square by the Cathedral: built in 1976 under Jean Lecanuet, closed since 1996, vanished in 2010. How was this even possible?