While there's plenty to see in the centre of Rome, keen walkers and cyclists shouldn't miss the opportunity to take a trip along Via Appia Antica, also known as the Appian Way, one of the oldest roads in Rome (dating from 312 bc). It was along the Via Appia that the followers of Spartacus were crucified, and it was here that St Peter is said to have met Jesus during his flight from Rome. The road is now a national park, and the southern end is closed to traffic.
There are cafés and other places to eat along parts of the road, but not once you get out into the country. If you're planning a long walk, consider taking a bottle of water and some snacks. There's also little in the way of shade so, if you're going in the summer, don't forget the sunblock!
Via Appia Antica
Things to See
There are several places along the Via Appia Antica which are worth visiting. Heading along the road from the centre of Rome (and out past the Aurelian walls through the Porta San Sebastiano), the first place that you'll come across is the Church of Domine Quo Vadis, which claims to have been built on the spot where St Peter met Christ. The church contains a marble slab in which are two grooves said to be the impressions of Christ's feet (the slab is actually a copy of the original, kept in the nearby church of San Sebastiano). The church itself dates from the 17th century.
A little further south is the aforementioned church of San Sebastiano, whose catacombs are among several sets either on or near this part of the road. They tend to be closed in the mid afternoon, so come out early in the morning or in the late afternoon if you want to visit them.
After passing the Tomb of Cecilia Metella (which was later developed into a castle), the Via Appia Antica begins to head out into the countryside. On either side are many more tombs, some of which are well preserved while others are little more than earth-covered mounds.
As with other sites in Rome where there are stone ruins exposed to the sun, during the summer the Appian Way is a good place for spotting lizards basking in the sun.
Visiting the Appian Way
There is a bus service, known as the "Archeobus," that runs from Termini station down past Circo Massimo and along the Via Appia Antica as far as the tomb of Cecilia Metella, as well as taking detours to the aqueducts and Casale Rotondo. The ticket is valid all day - allowing you to get on and off the bus as you like - and costs €8. It also gives some additional discounts, for example on entrance to some of the catacombs, and on the cost of renting a bicycle from the park centre.
parcoappiaantica.it is the official information site for the park.