The location of İstanbul could be placed in a circle, lying roughly at the intersection of the 41 st parallel and the 29th meridian. A number of the world’s important cities also lie on, or near the same parallel-cities such as Peking Salonika, Naples Madrid and New York. İstanbul is the place where the two continents Europe and Asia. It was founded at the point where the Black Sea is linked to the Mediterranean and the islands by the Sea of Marmara.
Istanbul is where roads link East and West, where the sea brings North and South together. This geographical feature of the city is further stressed by the presence of the Golden Horn, which throughout history has served as a natural harbor for ships of all kinds.
İstanbul was able to develop into three separate cities. The first of these is the historic part within the old city walls which is triangular in shape; this part of the city has a very ancient history. It has seen many different stages of development, and could rightly be described as its nucleus. Galata, which lies on the north bank of the Golden Horn, developed as a city in its own right, and is the nucleus of the many districts that have grown up around it during the past century.
Üsküdar was founded on the Asian side of the Bosphorus and, until the arrival of the Turks, was an unimportant settlement; it resembles a purely Turkish provincial township which has blossomed just outside of İstanbul, like a second city. During the time of the Ottoman Empire, the three parts of the city were referred to as Bilâd-ı selâse.
The summer months in Istanbul are generally hot and quite humid. The winters can be cold and wet, although not as extreme as other areas of the country. The sea temperature is creep up to 30 degrees in June, July and August, with very little rain. Spring and autumn are popular times to visit because of the comfortable climate, good for lots of walking and sightseeing, with highs between 15 – 25 degrees C, in April, May, September and October.
By the winter, the dry cold air mass from the Black Sea and cold damp front from the Balkans brings a chilly season with daytime highs of between 10 – 15 degrees C, and nights much colder. Although rarely falling to freezing point, there is the occasional light snow in the city.