Of all the roads that led to Rome, Via Appia Antica (built in 312 B.C.) was the most famous. It eventually stretched all the way from Rome to the seaport of Brindisi, through which trade with the colonies in Greece and the East was funneled. (According to Christian tradition, it was along the Appian Way that an escaping Peter encountered the vision of Christ, causing him to go back into the city to face subsequent martyrdom.) The road's initial stretch in Rome is lined with the great monuments and ancient tombs of patrician Roman families--burials were forbidden within the city walls as early as the 5th century B.C.--and, beneath the surface, miles of tunnels hewn out of the soft tufa stone.

These tunnels, or catacombs, were where early Christians buried their dead and, during the worst times of persecution, held church services discreetly out of the public eye. A few of them are open to the public, so you can wander through mile after mile of musty-smelling tunnels whose soft walls are gouged out with tens of thousands of burial niches (long shelves made for 2-3 bodies each). In some dank, dark grottoes (never stray too far from your party or one of the exposed light bulbs), you can still discover the remains of early Christian art. The requisite guided tours, hosted by priests and monks, feature a smidgen of extremely biased history and a large helping of sermonizing.

The Appia Antica has been a popular Sunday lunch picnic site for Roman families (following the half-forgotten pagan tradition of dining in the presence of one's ancestors on holy days). This practice was rapidly dying out in the face of the traffic fumes that for the past few decades have choked the venerable road, but a 1990s initiative has closed the Via Appia Antica to cars on Sundays, bringing back the picnickers and bicyclists--along with in-line skaters and a new Sunday-only bus route to get out here.

You can take bus 218 from the San Giovanni Metro stop, which follows the Appia Antica for a bit and then veers right on Via Ardeatina at Domine Quo Vadis? Church. After another long block, the 218 stops at the square Largo M.F. Via d. Sette Chiese to the San Domitilla catacombs; or, walk left down Via d. Sette Chiese to the San Sebastiano catacombs.

An alternative is to ride the Metro to the Colli Albani stop and catch bus 660, which wraps up the Appia Antica from the south, veering off it at the San Sebastiano catacombs (if you're visiting all three, you can take bus 218 to the first two, walk to San Sebastiano, and then catch bus 660 back to the Metro). On Sundays the road is closed to traffic, but bus 760 trundles from the Circo Massimo Metro stop down the Via Appia Antica, turning around after it passes the Tomb of Cecila Metella.

Of the monuments on the Appian Way, the most impressive is the Tomb of Cecilia Metella, within walking distance of the catacombs. The cylindrical tomb honors the wife of one of Julius Caesar's military commanders from the Republican era. Why such an elaborate tomb for such an unimportant person in history? Cecilia Metella happened to be singled out for enduring fame because her tomb has remained and the others have decayed.