Identify this – the underground city of Turkey

On February 14, 2017, the BBC posted a video entitled "Secret Subway City" of Turkey on its website, but the name of the city is not mentioned. The video ends with the sentence "The authorities hope to make it accessible to the public in 2018".

My question is … where can I find more information about this underground city?

Derinkuyu sounds like a potential candidate, but the Google satellite image does not seem to agree with what is shown in the BBC video.

Any ideas?