Some of Rome's attractions are among the best-known spots on Earth. Few visitors need to be told to visit the Colosseum or the Trevi Fountain during their stay in the Eternal City. But here's a list of some other worthwhile things to see and do that tourists may want to add to their itineraries, and the best part is that they won't cost a dime.

GLIMPSING THE POPE IN ST. PETER'S SQUARE

On Sunday mornings when the pope is in Rome, pilgrims, tourists and Romans flock to St. Peter's Square, intent on glimpsing the pontiff at his studio window as he speaks to the crowd below. Facing the basilica, the window to watch is next-to-last on the top floor of the Apostolic Palace. Just before the pope pokes his head out, a red curtain with the papal seal is hung from the windowsill. Many people carry flags or banners from their home countries or hometowns, giving the square a festive air.

Depending on what the pontiff says, the square often erupts in thunderous applause. His appearance starts at noon sharp and lasts about 15 minutes, so don't be late. The sun and presence of so many bodies can crank up the heat, so water bottles and hats are recommended. Even if the pope's out of town, the square is a worthwhile destination, with its 17th century colonnade cradling the area like two arms.

THE APPIAN WAY: ANCIENT ROME

The Ancient Appian Way was built in the fourth century B.C. by the censor Appius Claudius as a road to connect Rome with southern Italy. It's usually visited by tourists looking for its early Christian catacombs, but while the catacombs charge admission, a simple walk on the Appia is a wonderful way to feel the city's past beneath your feet.

The first part of the road from the center has no sidewalks and is unsuitable for pedestrians, but a good starting point is Cecilia Metella's tomb, a circular building of the Augustan age built for the daughter of a first-century B.C. consul. In the 4 kilometers (2.5 miles) from there to the city's outskirts, the road is often paved with its original basaltic blocks, and flanked by fragments of ancient tombs, statues and mausoleums.

Cecilia Metella's tomb can be reached by taking the Metro A line from Termini station to the Colli Albani stop, then riding the No. 660 bus for eight stops. Here you'll suddenly feel like you're in the countryside: Cars are rare, with the whole area closed to private traffic on Sundays, and sheep grazing in nearby fields. In summer, you can even pick blackberries from hedges along the way.

The road also has modern touches of glamour, since many rich villas are located on the sprawling countryside. In the late 1950s-early '60s "Dolce Vita" era, several of the villas were frequented by movie stars, and today's occupants still throw exclusive parties on weekends.

THE IMPERIAL FORUMS BY NIGHT: A ROMANTIC STROLL

The Way of the Imperial Forums, the street leading from Piazza Venezia to the Colosseum, is among the best-known places in Rome. By day, it perfectly represents the Roman Empire's lost greatness. The arches, temples, and row of statues portraying the emperors all testify to the pride that characterized Roman civilization 2,000 years ago.

But tourists who visit in sunlight should consider returning after sunset, when the Forums are transformed into a romantic spot with white, blue and green beams of light coloring the ruins. Lovers are often seen here embracing on the big fragments of columns scattered under the trees along the way.

SEE THREE STATES IN A KEYHOLE

A villa owned by the Knights of Malta atop the ancient Aventine Hill, at No. 3 on the Piazza dei Cavalieri di Malta, has a large entry door with a celebrated keyhole. If you peer through it, you'll have a perfectly framed view of the dome of St. Peter's Basilica.

Curiously, viewers can see three different states at once: the villa's garden in the territory of the Sovereign Order of Malta; the Vatican City State, where the Basilica is located, and a small portion of Italy in between.

If the weather is pleasant, stroll down the block to a tiny jewel of a park, the Giardino degli Aranci, or Orange Tree Gardens, where you can take in the cityscape and meandering river. It's especially popular with families on Sundays.

EUR NEIGHBORHOOD

A startling contrast to the wealth of ancient, medieval and Renaissance palaces in the city center can be found in the rationalist architecture of 1930s Rome in the EUR neighborhood. The area was designed as the host site for a proposed 1942 world's fair called Esposizione Universale Roma, or EUR. The expo, which Benito Mussolini had planned as a celebration of 20 years of Fascism, never took place because of World War II, but the neighborhood is still known by its initials as EUR.

The district's square, neatly laid-out buildings, connected by wide avenues, house government offices as well as several museums, including the popular Museo Preistorico ed Etnografico, which explores the development of Italian and world civilizations.

The EUR Magliana stop on the Metro B line is located in front of the neighborhood's most famous site, the so-called "square Colosseum": a huge, three-dimensional parallelogram pierced with arches. From there, one can easily walk to other buildings featuring the same monumental style associated with the Fascist era, such as the Palazzo dei Congressi (Congress Hall), built to host conferences and other gatherings.

There's also a park with a lake where Romans go kayaking or simply lie down on the grass, enjoying the view of the Basilica of Saints Peter and Paul.