“There’s no cement holding together the stone bases of Segovia’s aqueduct, it’s all about a balance of forces,” I said to him. The person I was talking to hadn’t been in Segovia for long, so little time in fact, that he admitted he still didn’t quite believe the aqueduct wouldn’t collapse on top of him every time he walked under its arches. “I keep looking up every time I walk under it, which I do rather cautiously, because I can’t help thinking that if there’s nothing holding these stones together, it means the whole thing can come down on my head at any moment,” said the visitor, as he admired the sheer robustness of Segovia’s most outstanding historical monument, with its sixty six arches built of granite. We walked over to the central arches together, where the aqueduct stands over twenty eight meters tall, and he looked at me and said, quite seriously: “I’m not worried any more. Something as beautiful as this has to be forever.”