The castle of Monolithos was built on the foundations of another, older castle, and lies about 236m high on an amazingly difficult natural terrain, which made its construction even more challenging, near the village of Monolithos. Under the orders of Grand Master D’Aubusson, and after having overcome the difficulties of transporting the building materials needed for its erection on the rocky outcrop, the castle of Monolithos was finally built, constituting one of the most important fortifications of Rhodes, due to its strategic location that allowed a clear view of the Mediterranean. The extremely challenging accessibility route and position also made it very difficult for enemies, including Ottomans, to seize the castle, forcing them to retrieve empty-handed.
The castle of Kritinia (Kastello, for the locals) is a Venetian castle built in the 16th century on a hill about 131 meters above the village of Kritinia. It is fairly considered the gem of the village as it offers a breathtaking view of the Aegean Sea, the island of Chalki and the islets of Strogyli, Makri, Alimia and others.
Due to its strategic location, which allowed complete monitoring of the sea and thus, the activities of pirates and other enemies, the site was chosen by the Knights of the Order of St, John to build the castle.