Long channelled, often invisible, water is nonetheless a vital element of our urban spaces. Both a resource and a threat when it transforms itself into floods and tsunamis, it is in any case no longer the private preserve of engineers and now concerns all the actors of the built world who are making it one of the main components of their projects. The surfaces of our cities, which have become impermeable in scarcely a century, are now punctuated by sunken gardens and storm basins. Available since May 15, issue no. 406 of L’Architecture d’Aujourd’hui proposes to review these projects and creations whose focus is the natural element. The floodable square in Rotterdam, public baths in Copenhagen, a humid zone in the centre of a Chinese city, an ecological park or renovated river banks in France… everywhere, water is being used to revitalize our cities as much as it is the subject of urban resilience strategies. It is a subject commented on in the framework of a conversation bringing together the ideas of different experts, a term – resilience – challenged in an alternative glossary that moreover dissects other ideas forming semantics concerning water in the city. And if there is a city that makes the natural element its standard, it is Singapore, which flaunts itself as a “hydro-hub.” So many subjects, among others, to discover in this issue.