The new major exhibition of Europa Expo will open in April 2023 in Calatrava's museum space at Liege-Guillemins station. The chosen theme is special because it does not refer to a particular period or event, a famous person or a specific subject. It deals with a universal, timeless theme: walls, but which, depending on the variation, encourages great freedom of approach and staging. It's a tremendous source of both emotion and reflection and has a clear educational value. In this context, the exhibition is not chronological, event-based or biographical, but makes its way through the diversity of reality and imagination of walls, their history and their memory.