The monolithos castle sits on the summit of a sheer, rocky outcrop that is 236m high. It was built on the foundations of another, older castle, in 1480, under the orders of Grand Master D’Aubusson, and when one considers the difficult terrain and the steep ascent that had to be negotiated in order to transport the necessary building material to the site, the existence of the castle becomes ever more precious. This fort, along with three others including that of Lindos was considered the most important of all the fortifications built on Rhodes as from here the knights had a clear view over a strategically-significant section of the Mediterranean. From the beginning of its existence until the Ottoman invasion, this fortress came under attack from the enemy on many occasions but no one was ever able to conquer it, probably because of its extremely difficult access route. Today, only a few sections of the fort have survived, but they are quite well preserved. Within the castle walls are two small medieval chapels, one of which, St. Panteleimon, a small, stone building painted a glaring white, has interior walls lined with lovely frescoes. The other chapel, St. George?s, is in ruin. Probably the most rewarding thing about attempting the steep climb to the top of this rock is the breathtaking views one can enjoy from up there, such as Akramytis Mountain to the north, Fourni Beach to the east, the settlement immediately below and Halki Island and a couple of other islets in the background. To reach the castle, you would have to drive to the foot of the cliff, park your car at a convenient spot in the area specially cleared for parking, and then climb the narrow little steps all the way up to the summit.