Geography of Turkey and Geology of Turkey
Satellite view of Istanbul and the Bosporus, connecting the Black Sea at the north with the Sea of Marmara at the south.
Faults in western Turkey are concentrated just southwest of Istanbul, under the Sea of Marmara and northern Aegean Sea.
Istanbul is located in northwestern Turkey within the Marmara Region on a total area of 5,343 square kilometers (2,063 sq mi).The Bosphorus, which connects the Sea of Marmara to the Black Sea, divides the city into a European side, comprising the historic and economic centers, and an Asian, Anatolian side; as such, Istanbul is one of the two bi-continental cities in Turkey among with Çanakkale. The city is further divided by the Golden Horn, a natural harbor bounding the peninsula where the former Byzantium and Constantinople were founded. In the late-19th century, a wharf was constructed in Galata at the mouth of the Golden Horn, replacing a sandy beach that once formed part of the inlet's coastline. The confluence of the Sea of Marmara, the Bosphorus, and the Golden Horn at the heart of present-day Istanbul has deterred attacking forces for thousands of years and still remains a prominent feature of the city's landscape.The historic peninsula is said to be built on seven hills, each topped by an imperial mosque, surrounded by 22 kilometers (14 mi) of city walls; the largest of these hills is the site of Topkap Palace on the Sarayburnu