In 138 AD, the Roman Empire was under the rule of Emperor Hadrian, who is known for his extensive building projects and efforts to consolidate the empire's borders. This year marked a period of relative peace and stability, often referred to as the Pax Romana, which allowed for economic growth and cultural exchange throughout the empire. During this time, Hadrian focused on strengthening defenses, particularly along the northern frontier, and is famous for constructing Hadrian's Wall in Britain. His reign also saw the promotion of arts and architecture, with significant contributions to the city of Athens and the establishment of the Pantheon in Rome.