We had just finished dinner in a normal street-front restaurant. Paid the bill and was about to leave when the waitress said "D'you want to see our cistern?" But of an odd question but we agreed and she took us back to the far corner inside to a glass panel.
Expecting to see perhaps an old spring, we were surprised to see a waiter in there having a cigarette. It was a glass door which he opened. Inside was a dark, dank room with a small illuminated archway. Following through the arch and series of ancient brick corridors we came upon this: