At the southern summit of the hill named Nissi stands imposingly the castle of Paralio Astros, the construction of which dates to the Frankish rule. It is a medieval fortress, which slowly developed into a powerful defensive complex.

Above the beautiful, traditional settlement of Karytaina, at an altitude of approximately 600 m., the castle of Karytaina stands majestically, overlooking the magical valley of the river Alfeios.