The University of Milan was founded in 1924 from the merger of two institutions that boasted a great tradition of medical, scientific and humanistic studies: the "Accademia Scientifico-Letteraria" (Scientific-Literary Academy), active since 1861, and the "Istituti Clinici di Perfezionamento" (Clinical Specialisation Institutes), established in 1906. By 1928, the University already had the fourth-highest number of enrolled students in Italy, after the University of Naples, Sapienza University of Rome and the University of Padua. Its premises are located in Città Studi (the City of Studies), the university district built from 1915 onwards (that is also home to the Politecnico di Milano), where scientific schools have its headquarters, and in several buildings in the historic city centre, which house the humanities schools.