The Golden Horn is a major urban waterway and the primary inlet of the Bosphorus in Istanbul, Turkey. As a natural estuary that connects with the Bosphorus Strait at the point where the strait meets the Sea of Marmara, the waters of the Golden Horn help define the northern boundary of the peninsula constituting "Old Istanbul", the tip of which is the promontory of Sarayburnu, or Seraglio Point. This estuarial inlet geographically separates the historic center of Istanbul from the rest of the city, and forms a horn shape, sheltered harbor that in the course of history has protected Greek, Roman, Byzantine, Ottoman and other maritime trade ships for thousands of years.