The first century Acqua Claudia still runs for an impressive length at the Parco degli Acquedotti, down near the Parco Appia Antica. Probably a little bit more pleasant to visit among the lush greenery of springtime, but a deserted summertime stroll is not a bad option either. As an added bonus, the park is always open and free to visit, so you don’t even have to worry about those pesky August closures!