The best green area close to Istanbul is, for sure, the Belgrade Forest. This extensive woodland area, located about 20km from Istanbul, makes for a pleasant city escape.
The Forest contains vast reservoirs that have supplied the city with water for centuries, going as far back as Byzantine times. Some of these historic reservoirs can still be seen today, most of which were constructed in the 18th century.
Belgrade Forest is named for the fact that during the 16th century, Sultan Suleyman the Magnificent resettled the area with Serbs in order for them to guard these crucial water supplies.