Cehennemağzı Caves

The Cehennemağzı Caves lie in the town centre of Karadeniz Ereğli, in Zonguldak province. Archaeological sources call them the Acheron Caves, while locals know them as the Mouth of Hell. A total of three caves were used in Roman and Byzantine times, and today the area is a protected historical site.

The Church Cave is a natural cavity that was partly levelled by cutting the rock. It served as a place of worship in the Roman and Byzantine periods, and it is thought that early Christians used it for secret prayers when Christianity was not yet accepted by Rome. Parts of the floor mosaics survive, with geometric, plant and figurative patterns. The Heracles Cave is where myth says Heracles, sent by King Eurystheus during the Argonaut expedition, dragged out Kerberos, the three-headed dog that guarded Hades. Foam from the animal's mouth was said to have created the aconite plant nearby.

In return for his services, the local Mariandynoi are said to have named the place after him, and the city was later called Herakleia Pontika. The Ayazma Cave has a large entrance and two halls, one of them filled by a lake that was regarded as holy and long used as a cistern for fresh water. The space on the left of the entrance is used for classical music concerts during festivals.