Consider this: Rome has been in the making for about 2,700 years.

According to legend, it was in Remus, sons of the god Mars, chose to build a city on the banks of the Tiber, where they had been suckled in infancy by a she-wolf. Ever since, Etruscans and Romans, early Christians and Renaissance popes, merchants and kings, politicians and painters have been devising marvels to adorn their city. Toward evening, when Rome's gold light washes over the old stones, the city has an almost tangible allure.

There is more to see per square inch in this city of just under 3 million than in any other. The subway, for instance, is never finished because work is halted every time diggers come across another ancient site. There are the Renaissance churches, the baroque palaces and squares, the ancient ruins, the elegant shops of restaurants and that vital mix of people that keeps Rome from being a museum and gives it its panache and snap.

In a city that is literally layered with things to see, I felt it must be impossible to know Rome in less tha, say, a lifetime. I had three days.

After poring over guidebooks and maps,. I realized that Rome is as compact as it is dense. Most of the major sights are in a relatively small area circumscribed by the Villa Borghese in the north, the railway station in the east, the Forum in the south and, in the west, just across the River Tiber, the Vatican complex. If I could not hope to know Rome in three days, I could at least see quite a lot of it, and I reckoned I could do most of it on foot.

The logical way to explore Rome would probably be to divide the sights into historical groups: ancient,medival, Renaissance, baroque. But given my limited time and also because I wanted to go everywhere on foot, I instead planned to cover the city in a way that seemed to make geographical sense. On the first day, I would take in the sights closest to my hotel, which was near the Villa Borghese, sights that would include the Spanish Steps, the Pantheon, the Piazza Navona. On the second day, I would venture a little farther, to the Capitol and the ancient ruins; and on the third I would make a stab at St. Peter's and the Vatican.

*Day 1. On the road from the airport, you catch sight of an ancient Roman aqueduct, scrubby pines and cypress, the shuttered terra-cotta and ocher villas. Entering the city itself, you notice the awful traffic, which eats away at old stone and endangers human equilibrium, but at least Roman drivers don't actually seem to want to kill you.

I checked into the elegant Eden Hotel on the via Lodovisi, with its grat city views. Then I washed up and set out for the Spanish Steps and the Piazza di Spagna, long the haunt of tourists.

At the top of the steps is one of the best perspectives in the city. On th steps themselves you see flocks of flower dealers, artists, lovers, drug dealers, writers writing deathless prose, vendors selling fake Vuitton bags, all the characters that make Rome a spectacle. In the square itself is the little house where Keats died, which is now a museum.

There is also Mrs. Babington's Tea Room, where, in honor of the English who ave long had a love affair with Rome, I had breakfast. Then I crossed the square to the elegant shopping streets aroundthe Via Condotti, where I also looked in at the Caffe Greco. Founded in 1760, it was here that Berlioz and Goethe, Tennyson and Wagner thought cosmic thoughts over their cappucciono. Then I headed soth and west toward the Pantheon.

"Awesome," said a young American. She was right.

One of the few great buildings from ancient times still intact (the Parthenon is another), the Panteon was originally built as a temple in 27 B.C. rebuilt by Hadrian after a fire in A.D. 118 and preserved for posterity by its dedication as a church by Pope Boniface IV in 609. Architects, including Thomas Jefferson, have drawn inspiration from its domed rotunda, and the building owes its structural genius to the Roman discovery of poured concrete.

From the Pantheon, I made my way to the Piazza Navona and settled in for a coffee on the terrace of Tre Scalini. The square is one of the great urban spaces. In the middle is the Fountain of the Rivers, the exuberant work of Gianlorenzo Bermini, the baroque artist whose buildings and sculptures changed the face of Rome in the 17th century, and opposite is the Church of Sant'Agnese, whose facade is by Francesco Borromini, another great practitioner of the flamboyant baroque style.

The Piazza Navona also vibrates with contemporary life. At Christmas, there are stret stalls selling sweets and rock records and decorations, and at all times there is a rich parade of Romans and tourists.

Near the Pantheon is my favorite Roman church, the charming Santa Maria della Pace, which has an alluring little cloister and, inside, Raphael's fresco of the Sybils. It's impossible in three days to see even a fraction of Rome's churches, so you make a random stab at a few. (All are detailed in any good guide and are easy to find on a street map.) You might visit: Il Gesu, the Jesuits' church with its stunning ceiling frescoes; San Giovanni in Laterano, the highest ranking of Rome's churches of the bishop of Rome); Santa Maria del Popolo for its art treasures; or Santa Maria Maggiore, with its 18th-century exterior and fantastic mosaics inside.

Wandering back to the hotel, I bought a pizza from one of the city's hundreds of pizzarie and returned to the hotel for a long siesta before dinner, a sensible and delicious Roman habit. At my first dinner in Rome, I was more conscious of the ambiance than of the food, although that would change on the second day. But the first night, as I arrived at the restaurant to meet some friends, what I noticed was the babble of good times. Everybody in the restaurant seemed to be talking to everyone else and everyone was smiling.

*Day 2. It's important to hit the street fairly early because many of Rome's sights shut up around 1 o'clock, so by 9 I was at the Revi Fountain where I threw in the coin that would guarantee my return to Rome. Then I headed along the Corso, one of Rome's main boulevards, toward the Capitol.

Dead ahead was the Victor Emmanuel Monument, finished in 1911 as a tribute to the reunification of Italy and its first king. As has been said, it looks like a wedding cake, although I prefer the description of it as a giant typewriter in marble.

Behind it, on top of a hill that you reach by a ramp or flight of stairs, is the Campidoglio, the piazza that was designed by Michelangelo and finished in the 17th century. In the middle is the Palazzo Senatorio, seat of Rome's municipal government; to the left is the Capitoline Museum, with a host of antiquities; on the right is the Palazzo dei Conservatori, which has five museums full of artwork; and at the highest point on this Capitolino Hill is the ancient Church of Santa Maria in Aracoeli, which was rebuilt in the 13th century. From the terraces of the Campidoglio you can look out over the ruins of ancient Rome, with the Colosseum (don't miss a climb up its ramparts) in the distance. Here, at the very heart of the city, the centuries converge; here you understand that all roads do, indeed, lead to Rome.

Visiting the Roman Forum requires stamina and a leap of imagination. I have a friend who simply takes a picnic and sits in the sun (even in December, Rome is often sunny).

The first emperor, Augustus, said, "I found Rome a city of bricks and left it a city of marble," and there's an awful lot of marble left, much of the ruins covered in plastic and scaffolding, each bit tagged with archeological and historical data.

YOu can take a guidfed tour or simply wander around the ruins. The most evocative for me is the House of the Vestals, the 10-year-old girls who were given over to keeping the sacred flame alive and to a life of chastity. Those who broke the vow, which lasted 30 years, were buried alive, according to legend.

After all that sightseeing, I needed sustenance, and dinner that evenig, as each evening in Rome, was wonderful. Ask the maitre d' to take away the menu and surprise you.

You may dine on hors d'oeuvres such as squid, octopus, mozzasrella, prosciutto (in summer with fichi, the succulent figs) or carpaccio, the thinly sliced raw beef glistening with olive oil. The pastas are familiar in name only, for the spaghetti alla vongole (tiny sweet clams), with white truffles; alla carbonara; the fettucine al triplo burro (three layers of butter) taste better in Rome. Try the saltimbocca for a main course, dish of veal, sage and ham that literally means "leap into the mouth," or tripe (trippa), for Romans are great with innards. A favorite of mine is fritto misto alla Romana -- vegetables, sweetbreads and brains fried in batter. And there are no artichokes (carciofi) on earth sweeter than those in Rome.

After dinner, do as all Rome does -- head for a cafe for dessert and coffee and a sample of latter-day dolce vita. Some of the best cafes for people-watching are Doney's and the Cafe de Paris on the Via Veneto; Bacaro, a wine bar near the Pantheon; and the Bar Rosati in the Piazza del Poplo.

*Day 3. I saved my last day for a visit to St. peter's and the Vatican, but first I walked across the Ponte Sant'Angelo over the Tiber to the Castel Sant'Angelo.

Begun in A.D. 135 and intended as a sepulcher for Hadrian, the castle became a fortified stronghold during the Middle Ages. Popes and antipopes fought for the building wiht its spectacular views of the city, and it has been refuge and prison, courthouse and art gallery and, in at least one case, the setting of a famous opera. Verdi's Tosca threw herself from the ramparts when she learned her lover was dead.

From the castle, I walked up the Via Della Conciliazione toward St. Peter's Square. It's hard to know how to see St. Peter's or the Vatican Museums, but with limited time, it's a good idea to figure out a few things you want to see: the Raphaels, for instnace, the newly restored frescoes of the Sistine Chapel, the church itself.

What St. Peter's reminded me is that, in many ways but especially in its flamboyance, Rome is close to the Orient. The baldachin, the extravagant canopy on pillars over the main altar (where St. Peter is buried), is rich, ornamental, extravagant. And there is no missing Michelangelo's "Pieta," now behind glass but brilliantly restored after the attack on it some years ago.

But St. Peter's, for all its grandeur, has a more intimate side: the confessionals, each with a sign posted to indicate the languages available within; and the old man who obviously considers this his parish church and whom I saw polishing one section of one altar rail over and over.

On my last day in Rome, my two favoriate moments were a view of Clement VII's bathroom in the Castel Sant'Anmgelo, decorated by Giulio Romano, a pupil of Raphael's, and that of an old nun in the Vatican post office.

Carefully, she stuck stamps on a large brown parcel that contained a pannetone, a Christmas cake, destined for Peking. As mies Van de Rohe said, in a different context, "God is in the details."