The ecological question is at the heart of current thinking. Zero waste is the way of life that everyone is gradually adopting. The trend is towards transformation, recovery and recycling. This principle, which is found in fashion as much as in our food, is also happening in architecture! There is a real desire to transform to better revitalise large ensembles, which are often put aside ... Here, the exhibition presents two emblematic projects: Bordeaux and Amsterdam, public and private places. "Ugly", "too old", "not in their place"... Large ensembles, or megablocks, are generally depreciated by the population. However, Le Corbusier's Cité Radieuse is an essential monument in Marseille, even though it is one! But 50 years after its construction, the Maison du Fada is starting to show signs of old age... As for all the other large ensembles besides ! More up to date, they can "spoil the view" according to some. But then, why did they build such imposing structures? Faced with the strong economic and demographic growth of the 60s and 70s, architects had to redouble their efforts to meet the rising demand for housing: to design, to build quickly while being practical. Quite a challenge! In Bordeaux, no less than 530 dwellings spread over three bars of buildings were saved by Lacaton & Vassal, Frédéric Druot and Christophe Hutin. In Amsterdam, NL architects and XVW Architectuur took up a major challenge by completely renovating the 500-unit apartment buildings, which they bought for a symbolic euro. A total renewal for old buildings that had been set aside for years!