At Dereağzı, there are two impressive Byzantine structures. On top of a strange, steep, triangular cliff stands a fortress, down in the valley a church.
The fortress protetcts a strategic point, overlooking three directions, with two rivers joining to form the Demre river. As a weird natural conincidence, the cliff stands as a left over from the mountains that opens up in southern direction. It has provided a perfect location for a military stronghold.
The first fortress was built here in the 6th to 5th centuries BCE by the Lycians. The Byzantines built a new fortress in the 9th and 10th centuries CE, following the wake-up call of the Arab attacks through the 8th century. The fortress had two inner layers of walls, which may not appear very visible. Easier to spot are the cisterns, vital to secure long time siege.
Towers and bastions were built to secure the weaker sides of the mountain cliff. At some points, it is quite scary to stand on top of the structures and look down a sheer drop.
Along the sides of the canyon, there are a few Lycian rock tombs. Not extremely impressive compared to f.x. Myra, but really interesting to note how this funerary method was dispersed even to small places in ancient Lycia.
There are no services out here.
Dereağzı is located conveniently for those coming from either Kaş or Myra/Demre. The road from Kaş is good, while the road to Demre, through the canyon is unsurfaced for some 20 km, but quite passable even for normal vehicles.