The water cistern in Stary Grad, Dubrovnik

Inside the walled city of Old Town (Stary Grad) they used to store water in this structure. Aquaduct-like pipes brought water to it, and obviously rain got in. The walled city in Dubrovnik, the darling of Europe the tourist brochures say, has never been conquered.

Beautiful place. A UNESCO World Heritage Site. One could do worse than try to see all the UWH sites.