Anadoluhisarı museum in istanbul , turkey:

The Fortress covers an area of about 7.000 m2. It has a 25m high central tower with five other watchtowers. Following the conquest of Constantinople, the building served as a military prison, though these days it's an open air museum. The Anatolian Fortress, which is directly opposite the Rumeli Fortress, was restored in the early 1990's.

 

Anadolu Hisari - Anatolian Fortress 

 Overview :

 

This imposing reminder of Ottoman might is situated at the narrowest point of the Bosphorus on the Asian side of Istanbul. Completed in 1394 by Sultan Bayezid I, the Fortress was constructed in preparation for the second siege of Constantinople by the Ottomans in 1395 and was used to control traffic entering the Bosphorus.

 

History of Anadoluhisarı :

 The fort was built between 1393-1394 by the Ottoman Sultan Bayezid I before he started his Second Siege of Constantinople in 1395 as a watch fort. Sultan Mehmet the Conqueror thickened the walls and paired it with Rumeli Hisari to completely control strait traffic, an important source of commerce for the Genoese, allies of the Byzantines. After the conquest of Istanbul, it was used as a military prison. First repairs were conducted by the local municipality in 1928, but extensive repairs were funded by the Ministry of Culture in 1991-3.

View of the castle in front of the sea in Turkey :

 

 Unfortunately, this fort is closed to visitors for the time being, despite restorations in the early nineties. It is still possible to visit it from the street, however. Notice its irregular pentagonal shape and main watchtower. There is a mosque inside as well. Look for the structures added later on, like the warehouse and houses. The complex now covers 7 acres.

Video of the castle :