The Tilbeşar Castle in the village of Gündoğan, 3 kilometers southeast of Yakacık, is situated atop the Tilbaşar Tumulus which was first inhabited in the Bronze Age. It is a 5-minute climb to the top to see the ruins.
The earliest evidence of settlement on the Tilbeşar dates from the Neolithic Age, and there are some levels dating from the Chalcolithic. The height of the mound is approximately 40 m.
The Tilbeşar Tumulus commanded important trade routes and strategic junctions during the Crusades in the 11th and 12th centuries, and a wall was built around the city that developed near the mound, and a well-fortified castle erected on the top. The castle here was mentioned in Assyrian sources, and it most probably dated from the Hittite period. The castle was captured by the Seljuks in the 12th century.
The nearby settlement called Abara was inhabited from prehistoric times and through the Classical ages. Excavations on the sides of the tumulus have revealed signs of settlement during the Early Bronze Age, Byzantine, Ayyubid period and the Crusades. Today, only some fragments of the Tilbeşar castle walls and towers remain.