Villa Celimontana, Rome
The Celian Hill, although within easy walking distance of the Colosseum and the forum, is an entirely different experience. remarkably quiet and peaceful, with some lovely churches (see tips on Santo Stefano Rotondo and Santi Giovanni e Paulo), the Case Romane 'hidden' Roman houses/street and the lovely, shady park of Villa Celimontana.
This is a nice place to take a picnic (there's a supermarket nearby in Largo Sanita Militaire, off Via Claudia), or a rest from the heat of midday. There are trees, and plants, and fountains (albeit rather small when I visited) , grassy slopes and a children's playground.
And rather good free toilets, hidden away behind a super construction of ancient Roman stonework which makes a very pretty rockery!
You can access the park from Clivio de Scauro, or from Via della Navicula (which follows on from Via Caudia).
Villa Celimontana is a small park on the Celio (Coelian) Hill, one of the nicest of the seven hills of Rome near the Coliseum. The park is not well known by non romans and it is a very nice place where to stop in the shade of the big trees in the summer. Go there after taking a walk along Via San Giovanni in Laterano and Via Claudia to visit four very interesting churches (I should add a tip on this). Villa Celimontana is also a very popular spot in the summer nights because many important jazz concerts are held there.Its entrance is just in front of the Navicella fountain.