Fatih Sultan Mehmet built the Roumeli Hissar Castlebuilt in the Istanbul Strait in order to took control of the sea expeditions between the Black Sea and the Marmara Sea, as well as built two opposite castles in the narrowest part of the Dardanelles Strait. There is Kale-i Sultaniye (Cimenlik Castle) on the Anatolian side and Kilitbahir Castle on the European side.

All entering and leaving ships were stopped and controlled when they came to this line. It is positioned in the narrowest part of the Strait so that cannon shots can be effective. Due to its location in parallel with the Cimenlik Castle in Çanakkale, mutual cannon fires intersected and it became extremely difficult to pass through the Strait. There was no area where a ship could pass.

The castle, which was built in 1462-63, was restoreted by Kanuni Sultan Suleyman. During this restoration, a castle (Sarıkule) was built and it’s wall surrounding the southern part (like outer sea Wall).

The castle was restored for the second time in 1870 by Sultan Abdulaziz. The original outer sea wall of the northern part does not exist today. The northern part of this section was rebuilt by II Abdulhamid in 1893-1894. The southern parts of the sea walls were used as cannon crenel. It has a restoration between the dates of 2011-2013. In 2015, a new exhibition - arrangement project was started.

If we look at it with a bird's eye view; it looks like a clover leaf, which is known as Kilid-ul Bahir, and it’s meaning is "Lock of the Sea". We can see lots of Many Ottoman period artifacts in Kilitbahir village, which developed with the construction of the castle. Fatih Mosque, Cahidi Sultan Mosque, Tabip Hasan Mosque, collapsed Kırklar Mosque, Usşaki Dergâhı (Ahmed Talibi Lodge), many fountains, traditional residences, two hammam and tombs around Cahidi Sultan Mosque are examples of these structures.

(Source: catab.ktb.gov.tr)