Rome was located in a strategic position in southern Europe along the Mediterranean coast, allowing it to develop extensive trade networks. It built major road and aqueduct infrastructure to support its growing territory. At its height, the Roman Empire stretched across Europe, North Africa and the Middle East. Internal political structures evolved from a republic to an empire under emperors like Augustus, Hadrian and Trajan. The empire's eventual decline was due in part to overspending on its large military and a shifting economic base away from agriculture.