By building the Rumelian Castle on the Bosphorus Strait, Sultan Mehmet the Conqueror not only took control of the sea lanes between the Black and Marmara Seas, but also built two castles facing each other at the narrowest point of the Dardanelles Strait. On the Asian side was the Kale-i Sultaniye (Çimenlik Castle), while Kilitbahir Castle was situated on the European side. All vessels entering or exiting the strait were intercepted and checked while they were on this route. The castle was positioned at the narrowest part of the strait to enable effective and unerring artillery shots. Due to its parallel location to the Cimenlik Castle in the Dardanelles, there is an overlap in the range of the castles’ artillery, rendering it difficult for vessels to pass as the entire strait at that point is covered by their field of fire.
The castle, built in 1462-63, was restored in 1541 by Sultan Suleiman the Legislator, and a fortification wall ramparting the southern section and a tower (Yellow Tower) at the outer edge of the wall were built during the restoration. The castle was restored for the second time by Sultan Abdulaziz in 1870. The original outer seawall of the northern section does not exist today. The northern part of this section was reconstructed by Sultan Abdulhamid II between 1893 and 1894. The southern parts of the seawalls were used as a firing port. The castle was recently restored between 2011 and 2013. A new merchandising project was launched in 2015.
The castle resembles a clover leaf in shape from an aerial viewpoint, and is named Kilid-ül Bahir which means “Lock of the Sea”. Several historical works from the era of the Ottoman State may be found in the Kilitbahir Village which developed with the construction of the castle. Examples of such Ottoman works are: Fatih Mosque, Cahidi Sultan Mosque, Tabip Hasan Mosque, the destroyed Kırklar Mosque, Ussaki Dervish Lodge (Ahmed Talibi Lodge), various fountains, traditional residences, two remnants of Turkish baths, and graves around the Cahidi Sultan Mosque.
