Amasya Castle is located on Mount Harşena which constitutes the northern horizon of the city center. It is also known as Harşena Castle. The mass of rock on which the castle is built is 300 meters higher than the city center and 700 meters higher than the sea level. The castle is claimed by some historians to have been built by Pontus King Mithridates. Other historians argue that the castle had been built by Karsan or Harsana and named after him. Throughout history the castle has changed hands numerous times and has been demolished more than once. Attacked during the reign of Persian, Roman Pontic, and Byzantine rulers over and over again, the castle was rebuilt in the aftermath of each attack. After the Turks conquered the area in 1075, the castle went through an extensive repair work. The Castle lost its military significance in the 18th century and was later deserted. The ramparts of the castle are built of broken stone whereas the upper sections are built of hewn stone. The castle has eight rungs of defense as it extends towards the banks of Yeşilırmak. In the middle of the inner yard, there is a vestibule, eight meters in diameter. The vestibule is carved into a rather tall rock and there are 150 stairs leading to the bottom of it. Also within the castle are cisterns, water reservoirs, remains of an Ottoman Hammam and Pontic rock tombs. Even today, most of the ramparts are in tact. The castle comprises of three districts, namely The Inner City (Hatuniye Mahallesi), Kızlar Sarayı and The Upper Castle (Harşena). There are mosques, hammams and Amasya Houses built on the antique walls rising from the northern bank of Yeşilırmak throughout Hatuniye Mahallesi which extends for as long as 800 hundred meters between the İstasyon Bridge and Hükümet Bridge. Access to this district, also called the Lower Castle, is possible through the Alçak Bridge, İstasyon Bridge, Hükümet Bridge and Mağdenüz Bridge across Sultan Beyazid Mosque. Kızlar Sarayı is separated from the Inner City (Hatuniye District) by the railway. Inner Castle The Inner Castle is also known as Enderun Castle. Nothing other than the bearing walls remain. The palace that was once here is believed to have been used until the 16th cc. The outer walls of the palace are known to have been built of stone whereas the inner walls were woodwork or brickwork. Seljuk Sultan Mesud I had the Inner Castle repaired in 1146. After Sultan Mesud made Amasya his capital, he had a mosque, a medresseh, a hammam and a palace built within the castle and he settled in Amasya where he lived here until he died.