King Carlos III sponsored the construction of this building, the St. Charles Hospital. It was originally built for the labourers working on the new houses at the Royal Site, due to the continuous accidents and illnesses that were occurring with ever greater frequency.
It was designed by Juan Esteban in 1771 and was inaugurated in 1773, but with only one part of it in use. It is a rectangular building and its perimeter walls have remained to the current time.
From 1781, the architect Juan de Villanueva was placed in charge of the building work. In 1801, he designed an extension of the main room, the cost of which was defrayed by selling buildings belonging to the Hospital.
After the revolution of 1868, the ownership of the building passed to the town, continuing to be used for the health purposes which had led to its construction.
In 1943, its name was changed to the Hospital de la Alcaldesa (the Mayoress's Hospital), making reference to Carmen Polo, who had been appointed as Honorary Mayor.
In the second half of the 20th century, several important rebuilding projects were undertaken. In 2002, it returned to its original name, becoming the San Carlos Health and Specialties Centre, or Centro de Salud San Carlos.