Via Appia Antica
All roads might lead to Rome, but it wasn't always that way. The Via Appia Antica, the "Queen of Roads," was built in 312 BC, and by 191 BC, extended all the way to the port of Brindisi, almost 310 miles southeast of Rome on the Adriatic Sea. The Via Appia Antica became Rome's most important road—and perhaps the most important road in the world—opening Rome up to the East.
By the time Julius Caesar was ascending to power, the road had been worn down. Sensing the importance of the road to Rome and its people, he became the curator of the Appian Way in 66 BC, and borrowed a significant amount of state funds to ensure its restoration. The move gained him political support, which proved crucial in advancing his political career.
To explore the road (and the three catacombs that are open to the public that line it), take the metro out to the Appia Antica stop and head to the Appia Antica Regional Park Information Point. Here, you can buy a map of the park and rent bikes. The park also runs tours, but those must be booked two weeks in advance.