Hadrian was one of the most powerful and respected emperors in history. Considered one of the five "good emperors," he reigned in an era that chronicles of the time describe as the happiest in Antiquity. Beginning in 117 A.D., Hadrian ruled an empire encompassing three continents for 21 years. Hadrian ended the expansionist policies of his predecessors, consolidated the provinces, and became a great emperor promoter of peace and prosperity. He left an immense legacy as he invested in infrastructure and the arts in every part of his boundless kingdom. Not only Rome and Athens, but also many other cities of the empire owed him the construction of new buildings and the execution of impressive restorations.