Constantinople as a Geographic Crossroads

The site of Constantinople was first settled as the Greek colony of Byzantium, traditionally founded around 657 BCE by settlers from Megara following advice attributed to the Delphic oracle, on a triangular peninsula commanding the Bosphorus strait — the sole navigable passage linking the Black Sea to the Sea of Marmara and, beyond it, the Mediterranean — at very nearly the narrowest point of land separating Europe from Asia Minor. The peninsula's northern flank was sheltered by the Golden Horn, a deep, naturally defensible inlet that provided an outstanding harbor, while its position meant that any land or river trade moving between the Balkans and Anatolia, and any sea trade moving between the Black Sea grain-producing regions and the Mediterranean, could be observed and taxed from the city's walls.