The original project designed by Lluis Domènech i Montaner consisted of 48 pavilions built according to a design pattern and distributed around two main axes (north-south and east-west) by 50 meters wide, with additional streets 30m . These main areas, located in the diagonals of the square closed the set, forms a cross which is the ubiquitous symbol of the hospital and reference to the original hospital.
Twenty-five pavilions should be a flat, two-story eleven and twelve used for various services. All of them had the basement and were interconnected by underground tunnels because it could move patients and staff without having to go outside. They were also features galleries techniques to locate facilities and pipelines outside the pavilions, facilitating maintenance.