The topic of my master thesis is the transformation of a sports facility in a multifunctional building. The case study is the Feyenoord Stadium, de Kuip, in Rotterdam. Because of its monumental, architectural and historical value, the demolition of the stadium for a new sports facility was not considered a solution. An in-depth study of the history and architecture of de Kuip led to the design of the new functions that are divided into public and private spaces, following the existing steel structure of the stadium on two levels. The ground level includes the Feyenoord’s museum, new sports facilities, commercial areas and a small hotel reception, while the soccer field is replaced with a public park. The upper level collects the hotel rooms and the residential spaces, which include four typologies of apartments and common and aggregation places. Lastly, a study on the optimization of the obscuring of the glazed facade was done with the Grasshopper software, elaborating a mechanical system that follows the position of the sun, giving the users the best lighting comfort during the day.