A rickety turnstile stands between the not-very-distinguished city of Castellammare di Stabia, 19 miles south of Naples, and Stabiae, a cluster of villas built by wealthy Romans more than 2,000 years ago. Walking through the ineffective barrier between the two, as I did in July, feels like taking a trip back to the 1st century B.C., when Stabiae became a resort town. Putting aside the discomfort of walking on a dusty, unpaved lane in sandals that seem to attract rather than repel stones, discovering where and how patrician Romans spent some of their leisure time is the kind of sightseeing people who love art and history live for.