Not that I don't you, as it makes sense, but I can't see any cisterns on satellite view. It does say the town was completely razed in 1233, so it might have existed. My next question would be how they collected the water on top of a hill
They definitely have access to water inside the town.
If there wasn't, building it there would be pointless, attackers could just wait a week instead of assaulting it.
Just imagine centuries inti the future and a guy looking at this says it's shaped like and image of Xtallll, and therefore is meant for communications with extraterrestrial beings.
Reality is great because you can create stuff like this and nobody calls it "hacky" or "an overwrought metaphor that's about as deep as a plate of cereal".
The English wikipage is unsurprisingly not thorough on this small Italian city. The Italian wikipedia page has this picture showing the same thing from the side. The front view is obviously taken from an angle to accentuate the human appearance of the townscape.
Once upon a time attacks came from just land (or sea if near one), and walls and high ground let you literally roll boulders to crush your foes (yay catapults). WW1, Maxim guns, planes, and bombs made this all pointless (but absolutely no fear of floods)