The valley, named “Vrathes” meaning “rocky place” in Greek during the Ottoman period, is now known as Beyderesi today. It is located very close to the center of Mustafapaşa, about 1 km north of the village. There is the Church of St. Basilios, one of the most significant churches of Mustafaşa built and painted during Ottoman period, on the eastern slope of the valley. In addition, the valley contains interesting fairy chimneys in its unique form, many shelters carved into the rock, and rock tombs from the Roman period.