The new coffee bar Calicantus in the court of the Sforza Castle in Milan fits in well with the architecture surrounding without competing with the historical pre-existence, but becomes a favorite point for its contemplation. The project starts after winning the municipal competition. The announcement presented clear and binding guidelines: use of noble materials, greatest possible transparency, absence of stable foundations and short realization time. The combined planning of ARCò and Ariano offices conceived a modular steel and glass building, so that the standardization could facilitate the prefabrication in the workshop and minimize the building operation to the assemblage of the different elements. Thanks to this approach, we realized the building in only four weeks. The galvanized and varnished steel structure becomes the language: the main portals identify the façade ribbing, the roofing boxlike structure frames in a grill the horizontal image of the castle and the large glass walls create a continuity between the coffee shop area and the castle court (when they're closed, they frame the "Portico degli Elefanti", the entrance from"Piazza del Cannone" and from the "Rocchetta courtyard"; when they are open the coffee shop becomes physically and perceptually permeable). The building sits on a steel-beam platform, placed on a stabilized layer and the flooring stones designed by BBPR studio define the access to the "Rocchetta" and the "Ducale" courtyards. The wood floor and the outdoor refurbishment, solve the coffee shop revised space.