The development of the most active period of Persian medicine occurred in the ancient city of Gondeshapur, between the third and seventh centuries. Rebuilt between 256 and 260 by Shapur I, the second Sassanid monarch, Gondeshapur is said to have welcomed the first hospital and the consequent study of medicine, mainly based on the Greek system. It has also been mentioned that these teachings would be expanded by his successor, Shapur II. However, both statements need solid confirmation. Nestorian priests-professors and other academics expelled from the Byzantine Empire gave fundamental encouragement to cultural and medical development in Gondeshapur. With Khosrow I, Gondeshapur became a cosmopolitan city with studies of medicine, philosophy, eloquence, and music. The medical studies were conducted in an academic setting, and practiced in a hospital, with the documentary support of a library which would be provided with the main texts, mainly of Greek, Syrian, and Indian origin. The Byzantine-inspired hospital system of Gondeshapur with its own management, organic system, and differentiated personnel, was later reproduced in several cities of the Middle East and medieval Europe under Islamic rule. The academic prestige and functionality of Gondeshapur, which peaked in the seventh century, began to decline in the following centuries apparently due to the creation of similar intellectual and hospital centres in Baghdad, by the Caliph al-Mansur, and the subsequent transfer of doctors, technicians, professors and other personnel from Gondeshapur, to ensure there the operation of hospitals and also medical studies. This cultural policy was continued and expanded by al-Mansur successors, in particular by the Caliph al-Ma’mun, until the tenth century.