When the Republic of Turkey was born in 1923 after the War of Independence, Kemal Atatürk moved its capital to the city of Ankara.However, Istanbul has continued to expand dramatically; today its population is approximately 14 million and increases at an estimated 400,000 immigrants per year. Istanbul is divided in three by the north-south Bosphorus Strait (Istanbul Bogazi), the dividing line between Europe and Asia, the estuary of the Golden Horn (Haliç) bisecting the western part and the Sea of Marmara (Marmara Denizi) forming a boundary to the south.Most sights are concentrated in the old city on the peninsula of Sultanahmet, to the west of the Bosphorus between the Horn and the Sea.
Istanbul (Turkish: İstanbul) is Turkey's most populous city as well as its cultural and financial hub.
Located on both sides of the Bosphorus, the narrow strait between the Black Sea and the Marmara Sea, Istanbul bridges Asia and Europe both physically and culturally.
Istanbul has a high annual average rainfall of 844mm (which is more than that of London, Dublin or Brussels, whose negative reputation Istanbul does not suffer), with late autumn and winter being the wettest, and late spring and summer being the driest.
Although late spring and summer are relatively dry when compared to the other seasons, rainfall is significant during these seasons, and there is no dry season as a result.
If there is a negative reputation that Istanbul does suffer from, it is the high annual relative humidity, especially during winter and summer with the accompanying wind chill and concrete-island effect during each respective season.
Summer is generally hot with averages around 27ºC during the day and 18ºC at night.
Summer is also the driest season, but it does infrequently rain.
Showers tend to last for 15-30 minutes with the sun usually reappearing again on the same day.
It was finally conquered by the Ottoman Sultan Mehmed II on , an event sometimes used to mark the end of the Middle Ages.