Thanks to the collection of Arabic tales “A Thousand and One Nights,” Harun al-Rashid became perhaps the most famous ruler of the Muslim world. However, the personality of Harun and the real events that took place during his reign, as a rule, remained in the shadow of his fairy-tale prototype. The book by the French orientalist Andre Clos is intended to show readers the true face of the legendary caliph. If most readers know Harun al-Rashid as a pampered and capricious sovereign, enjoying life surrounded by concubines and musicians in his Baghdad palace, then the reality is completely different: from childhood, Harun was forced to fight for life and power. The youngest son of Caliph Mu'tasim and a Yemeni slave, he barely survived the reign of his older brother. Having become caliph, Harun faced many difficulties: he inherited from his ancestors unresolved disputes between the descendants of the Prophet Muhammad, who claimed power, and religious strife between Sunnis and Shiites. The huge Muslim empire, inhabited by a variety of peoples, was not easy to keep in obedience. But difficulties only strengthened Harun’s character: he was known to his contemporaries primarily as a successful military leader who successfully fought the Byzantine Empire and suppressed internal rebellions with an iron hand. The caliph also had to maneuver among the intricacies of palace intrigue: suspecting the Barmakids family, which had served him faithfully from the very beginning of his reign, of treason, Harun without hesitation sent him to the scaffold. However, this portrait would be incomplete if the author of the biography did not remember Harun’s role as a patron of art and science. It was this caliph who gave a powerful impetus to the cultural development of Baghdad, which under him became the most populous city in the world. Under Harun, the capital of the caliphate experienced a rapid economic breakthrough: merchants and sailors visited the largest markets in Europe and Asia, turning Baghdad into the economic center of the world.