Cehennemağzı Cave

The Cehennemağzı Caves (Cehennemağzı Mağaraları) are a series of three quarries lined side by side, in the Karadeniz Ereğli district of Zonguldak Province, northern Turkey. One of the quarries was used as a church in early Christianity, in other words mining was abandoned before. The "cave" is a proper name, not an actual geological classification. Also its easy to mix it up, as those quarries have speleothems, which were growing since the mining ended about 2,000 years ago, so they have decent size.

Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).