Outside the Monolithos village is the medieval castle, built on top of a 100m rock. It was built in 1480 by the Knights of Saint John to protect the island from attacks. In fact, this castle was never conquered. The Castle of Monolithos is widely ruined today but it offers great views of the sea and the two islets opposite to it. Inside the castle, there is a small working chapel dedicated to Agios Panteleimon (Saint Pantaleon).
Access to the castle is by a staircase cut into the rock. The steps, whilst not particularly steep, are quite slippery simply due to the numbers of visitors wearing them away. On the climb up to the top, you are likely to see hundreds, if not thousands, of small piles of rocks from 3–10 in number. These piles are left there by the visitors as a form of a memento.
References:Kakesbeck is one of the largest medieval fortifications in Münsterland and the oldest castle in Lüdinghausen. The imposingly grown complex originated in 1120 as a motte, a small hilltop tower castle. After numerous changes of ownership, the castle was extended onto two islands, but it was not until the 14th century that it underwent significant alterations and extensions under the von Oer family. The estate experienced its heyday in the middle of the 18th century, when it covered an area of almost one square kilometre and consisted of five further outer castles in addition to the core castle, which were secured by ramparts and moats.
The well-maintained condition of the castle today is thanks to the late Wilfried Grewing, the former lord of the castle. The foundation named after him has been particularly committed to preserving the property since 2020.