Famously, Rome’s best cappuccino is to be had at Caffè Sant’Eustachio, named for the basilica opposite the coffee house that venerates the second-century martyr St Eustace, the Roman general who, according to legend, was roasted to death inside a bronze statue of a bull. The coffee’s reputation is deserved, in my opinion, but the service is so laid-back that it would be quicker to grind your own cup from the beans they now sell so that fans can recreate the experience at home. As I wandered home from a gentle pick-me-up there recently, through Piazza della Rotonda, I stumbled upon the curious sight of hundreds of young people standing mutely facing the Pantheon, heads bent over books. They are the Sentinelle in Piedi, or Sentries on Foot, and they stage one-hour s