Sultan Abu Amr Othman is the last of the powerful sultans of the Hafsid state (625-981 AH / 1227-1573 AD). Thanks to his personality, wisdom, firmness and justice, this sultan was able to maintain the state he inherited from his fathers and grandfathers safe and stable throughout his long reign that lasted more than 54 and a half years. He is the longest-reigning Hafsid sultan, the most famous and the closest to his subjects in affection. How could he not have been, as his reign was distinguished by the many works and achievements he provided to serve his subjects, through which he gained the love and loyalty of his subjects.Thus, peace prevailed and security spread throughout his reign until it became a prominent feature of his. For this reason, we decided to shed light on this topic, as it directly affects people's lives. We dealt with the topic in two sections. In the first section, we discussed the personal biography of the sultan, starting from his birth, upbringing, characteristics and a glimpse of his era, up to his assumption of power and finally his death. As for the second section, we explained the most important monuments that abounded in the era of this Sultan according to their importance to the public, starting with religious facilities, and corners, all the way to schools, houses of learning, and many others.