It is believed that the castle was built in BC VIII. By the Miletus immigrant collonies which settled down in Sinop. Castle has been improved and developed in years under the domination of many civilizations. It was also an important observation and defending place for the ones live in the area.  The total bastion and towe lenght is around three thousand mt. Bastions having an eight mt width and 25 mt height are   inaccesible  by the invaders.

It was used for centuries as a prison between 12 th century and 21st century.

The unique location by the sea  and glorious look of the structure is a must  place to see in Sinop