Anatolian Fortress or Anadoluhisar Fortress (Anadolu Hisary, Anatolian Castle / Anadoluhisarı, Turkish name: Anadolu Hisarı) is a small fortress (fort), which is one of the oldest architectural structures in Istanbul.
The fortress is historically known as Güzelce Hisar, which means "Beautiful Castle".
The fortress is located on the Asian side of Istanbul near the Bosphorus Strait and near the Kucuksu Palace.
The fortress was built as a guard fort in the narrowest part of the Bosphorus Strait (660 meters) under the Ottoman Sultan Bayezid I in 1393-1394 and was intended to prepare the siege of Constantinople (now the city of Istanbul).
The fort had a square main tower 25 meters (82 feet) high in the walls of an irregular pentagon with five watchtowers at the corners.
Mehmed I's grandson, Sultan Mehmed II, fortified the fortress with a two-meter wall and three additional watchtowers, and also added additional extensions, including a warehouse and living quarters. As part of his plans to launch a new military campaign to conquer Constantinople, Mehmed II on the opposite side of the Bosphorus (European part) opposite Anadoluhisari in 1452 built Rumelihisari Fortress. After that, the two fortresses worked in tandem in 1453 to restrict all sea traffic along the Bosphorus, thereby helping the Ottomans achieve their goal of making the city of Constantinople (later renamed Istanbul) their new imperial capital.
After the Ottoman conquest of the city, Anadoluhisari served as a customs post and a military prison, and after a few centuries fell into disrepair.
Then the Turkish Ministry of Culture started restoring the fortress. Today, only a part of the fortress remains, and it is clearly visible from the Bosphorus and the nearby street.
The Geksu stream flows near the fortress, which makes the views of the fortress and the surrounding area even more picturesque.
Coordinates of the Anatolian Fortress: 41°04'55.0"N 29°04'01.0"E (41.081944, 29.066944).
All accommodation facilities in Istanbul, including in the historical center, on the European and Asian sides of the city, can be viewed and booked here 
