<P> Constantinople was founded by the Roman Emperor Constantine I (272--337 AD) in 324 on the site of an already - existing city, Byzantium, which was settled in the early days of Greek colonial expansion, in around 657 BC, by colonists of the city - state of Megara . This is the first major settlement that would develop on the site of later Constantinople, but the first known settlements was that of Lygos, referred to in Pliny's Natural Histories, Apart from this, little is known about this initial settlement, except that it was abandoned by the time the Megarian colonists settled the site anew . The site, according to the founding myth of the city, was abandoned by the time Greek settlers from the city - state of Megara founded Byzantium (Greek: Βυζάντιον, Byzántion) in around 657 BC, (14) across from the town of Chalcedon on the Asiatic side of the Bosphorus . </P> <P> The city maintained independence as a city - state until it was annexed by Darius I in 512 BC into the Persian Empire, who saw the site as the optimal location to construct a pontoon bridge crossing into Europe as Byzantium was situated at the narrowest point in the Bosphorus strait . Persian rule lasted until 478 BC when as part of the Greek counterattack to the Second Persian Invasion of Greece, a Greek army led by the Spartan general Pausanias captured the city which remained an independent, yet subordinate, city under the Athenians, and later to the Spartans after 411 BC . A farsighted treaty with the emergent power of Rome in c. 150 BC which stipulated tribute in exchange for independent status allowed it to enter Roman rule unscathed . This treaty would pay dividends retrospectively as Byzantium would maintain this independent status, and prosper under peace and stability in the Pax Romana, for nearly three centuries until the late 2nd century AD . </P> <P> Byzantium was never a major influential city - state like that of Athens, Corinth, and Sparta, but the city enjoyed relative peace and steady growth as a prosperous trading city lent by its remarkable position . The site lay astride the land route from Europe to Asia and the seaway from the Black Sea to the Mediterranean, and had in the Golden Horn an excellent and spacious harbour . Already then, in Greek and early Roman times, Byzantium was famous for its strategic geographic position that made it difficult to besiege and capture, and its position at the crossroads of the Asiatic - European trade route over land and as the gateway between the Mediterranean and Black Seas made it too valuable a settlement to abandon, as Emperor Septimius Severus later realized when he razed the city to the ground for supporting Pescennius Niger's claimancy . It was a move greatly criticized by the contemporary consul and historian Cassius Dio who said that Severus had destroyed "a strong Roman outpost and a base of operations against the barbarians from Pontus and Asia". He would later rebuild Byzantium towards the end of his reign, in which it would be briefly renamed Augusta Antonina, fortifying it with a new city wall in his name, the Severan Wall . </P> <P> Constantine had altogether more colourful plans . Having restored the unity of the Empire, and, being in the course of major governmental reforms as well as of sponsoring the consolidation of the Christian church, he was well aware that Rome was an unsatisfactory capital . Rome was too far from the frontiers, and hence from the armies and the imperial courts, and it offered an undesirable playground for disaffected politicians . Yet it had been the capital of the state for over a thousand years, and it might have seemed unthinkable to suggest that the capital be moved to a different location . Nevertheless, Constantine identified the site of Byzantium as the right place: a place where an emperor could sit, readily defended, with easy access to the Danube or the Euphrates frontiers, his court supplied from the rich gardens and sophisticated workshops of Roman Asia, his treasuries filled by the wealthiest provinces of the Empire . </P>

Why was constantinople a good location for the capital of the byzantine empire
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