This research thesis analyses the architecture of Aires Mateus brothers and the conditions in which they design, while focusing on the void and how it is used in their own architecture and in Portuguese architecture in general. Through the reference of their influences and the main representatives of the Portuguese architecture, we begin to examine how each architectural creation is made and how it starts to be sculpted, according to the way they design and the methodology of their architecture. By seeking the significance of void and the terms of their architecture, we examine how they are connected with the past history of Portugal and if they are opposed by it or they create their own innovative integration method, not only in Portuguese architecture, but in architecture in general.