There's no villa at the Villa Gregoriana (Largo Sant'Angelo and Piazza del Tempio di Vesta; 39-06/3996-7701;; admission $5) in Tivoli, 22 miles east of Rome—just the ruins of a second-century B.C. Roman consul's mansion once renowned for its garden fountains. The location was a favorite backdrop for artists like Corot and Fragonard because of the Aniene River (which pours over a 394-foot-tall cliff and snakes through limestone grottoes), but it has been off-limits and considered landslide-prone for a decade. Now, after a $5.5 million overhaul led by the Italian Fund for the Environment, this site recently reopened. Crews dragged away tons of litter and blackberry thickets, shored up precipices, and converted a former school into a terra-cotta–colored stucco visitors' center, designed by "starchitect" Gae Aulenti. Next on the Fund's to-do list: gentle scrubbings for two travertine-marble ancient temples and pruning in the laurel and oak groves. In the meantime, hikers can explore the grottoes (wear rubber-soled shoes, and remember to duck your head), pausing for views of the temples. —EVE KAHN

Villa Gregoriana