The Appian Way (Via Appia), an important Imperial Roman road dating from the 4th century BC, was built to quickly move supplies and Roman soldiers to strategic points of the Roman Empire. The Appian Way was the first and most important Roman road, stretching from Rome to Brindisi on the southeast coast of Italy.
It was the work of architect Appius Claudius Caecus (hence the road's name). You can still walk the long straight cobblestone road, and along the way are catacombs and churches.
As the Roman Empire began its terminal decline, Rome was the focus of attacks and invasions by barbarians. In the third century AD the Aurelian Wall was built around the city's seven hills for protection. The Aurelian Wall had many gates, one of them being the Porta San Sebastiano (which still stands today). It was once called the Porta Appia because it marks the point where the Appian Way begins. The gate now contains a museum about the wall and Rome's ancient gates.
One of the best places to begin exploring the Via Appia is at the Parco Regionale Dell'Appia Antica. Metro line A has a stop at Parco Appia Antica.