The architect commissioned to build the Hospital de Sant Pau was Lluís Domènech i Montaner.

The infirmaries and their general services were split into 48 large separate pavilions, joined together by underground galleries.

The heating, water, gas and electricity services were installed in the open.

Two main diagonal routes in the shape of a cross - each 500 m long and at least 50 m wide - separate the buildings. The other routes are 30 m wide.

The main entrance, at the southern corner (nearest the city and the sea) starts with a plaza that is 65 m by 45 m, separated by railings from carrer Coello (now carrer Pare Claret) and from carrer Igualtat (now carrer Cartagena).

Opposite the Administration building there is a free space that is 93 m x 65 m. The building's vestibule is 17 m x 14 m, and is open on all sides.

The rooms of the pavilions for the patients are 7 m high, and are elongated rectangles 25 m x 8 m.

The Joint Hospitals (before 1936)

Program of the Joint Hospitals

The Program for the hospitals was confirmed by a technical commission consisting of

- Bartomeu Robert. Professor of the Faculty of Medicine, chosen by Barcelona Council. He was succeeded by Pedro Esquerdo.
- Emerencià Roig. Member of the Royal Academy of Medicine. He was succeeded by José de Góngora.
- Joaquim Duran. A doctor with a permanent position at the Hospital de Santa Creu.

The original program consisted of:

I. General service buildings
II. Infirmaries and Annexes
Section 1. Surgery and Medicine (men, non-infectious)
Section 2. Surgery and Medicine (women, non-infectious)
Section 3. Infectious diseases (men)
Section 4. Infectious diseases (women)
Section 5. General hospital for children