Does anyone remember the name of the underground city in Turkey that the Rick Steves tour went to some years back?
Google suggests Derinkuyu
The Kaymakli Underground City is just 6 miles away from Derinkyu. We visited both by bus on the same day.
My 2023 Rick Steves tour went to Kaymakli.
There is also a place called basilica cistern in istanbul I recommend you to visit
Currently I am in Istanbul as you have mentioned basilica cistern is incredible to visit !!