CPN 21 is a project by Diego Grandi that reinterprets a penthouse apartment in a stately building from the 1920s in Milan. The new, rigorous and functional layout is the basis on which the other characteristic elements of the project have been inserted, such as the geometric decorative accents that characterize the apartment's space and are examples of the designer's graphic language. The Escher-like surfaces in the kitchen and bathroom, created with Lea Ceramiche's Slimtech porcelain stoneware collections, play with space and create an alienating effect thanks to full colors and rhythmic geometries.