Roman Empire

The Roman Empire at its height under Trajan controlled 5 million square kilometers and 70 million people—21% of the world's population, a demographic reach that the Islamic Caliphate (Umayyad) fell short of matching. Its legal systems, based on Roman law, underpin most European frameworks, and its Latin language evolved into five major Romance tongues spoken by 900 million today. The empire's 2,000-year-old road network, spanning 400,000 kilometers, remains a blueprint for infrastructure, rivaling the British Empire's sea-lane innovations in lasting impact.