"Take the bus," our new Parisian neighbor said. "You can catch the 72 right here at the corner, and it's one of the best tour buses in Paris."

We had heard over and over about the famed Metro, that it was one of the best subways in the world. And we learned later that in fact the Metro is fast, fun and a little funky on the older lines, and there is virtually no place in the city that is more than a short walk and subway ride away. But overshadowed by the Metro's renown is an efficient bus system that has the distinct advantage of operating above ground, where you can see the Paris between the Metro stops and monuments.

We walked to the corner tabac and purchased a carnet de Metro, a set of 10 tickets good for both the bus and the subway. The cost was about half the cost of buying tickets individually from the bus driver. We also bought 10 half-price tickets (demi-tariffs) for our 5-year-old.

We enjoyed the five-minute wait for the bus to arrive, amid the Monday morning bustle along the Avenue de Versailles. Traffic was heavy but moving, a sign that the rush hour was winding down. The pastry shops, displaying their tempting creations in the front windows, were open and doing a brisk business. The daily routine of shopping was just beginning. Nearby a butcher was rolling up his shutters, and across the street a shopkeeper was cranking up the canopy over her store. The light on a green cross that marks all Parisian pharmacies had just come on.

It was all so commonplace. It was all so fascinating. Paris was being rediscovered for the billionth time.

A small crowd had gathered around the bus stop, and most boarded a bus bound for the Opera House. Our 72 was not far behind.

We took out two tickets each and stamped them in a small machine by the driver as we boarded the bus. I tried to show the driver that we had two tickets, for the two-zone ride, but he took little notice of us. Parisian bus drivers drive. Ticket checking is done by a group of inspectors who randomly board buses and subways looking for scofflaws, who are taken off and assessed hefty fines if discovered.

I felt uneasy about the system -- wanting confirmation that I was playing by the rules -- and kept our tickets at hand for the whole trip in case anyone asked to see them. No one did.

The bus was nearly full, but we found seats at the back where we could see the sights in both directions. On the semicircular, couchlike seat (an open platform on some buses in the summer) we were nearly surrounded by large windows that stretched from shoulder level nearly to the roof. And we were off on our tour of the city.

We had picked up the bus about three miles into its route, which runs from Pont de St. Cloud, on the western outskirts of the city limits, to Ho tel de Ville, in the heart of Paris.

For a mile or so we cut through a canyon of apartment buildings that provide space at street level for small shops, restaurants and glass-fronted brasseries and cafe's that spill out onto the broad sidewalks in the warmer months.

Cars darted around the bus dangerously as we passed the typical but lovely square at Pont de Barcelone. A woman was selling cut flowers at the Metro stop at the square, and a shopkeeper was setting up folding tables along the sidewalk, a sure sign that he was holding a sale.

Leaving the canyon, we could see the modernistic Radio France building, and soon the bus met up with the Seine River, whose course we would follow the rest of the way.

The passengers on the bus -- apparently late commuters, students and shoppers headed for the stores downtown, all veterans of the trip -- were taking little notice of Paris as it unfolded outside the window. And as we approached the Eiffel Tower and Trocade'ro, they seemed to take the oohs and aahs coming from the back of the bus with indifference. Parisians, after all, have been coexisting with visitors for centuries.

After passing Pont Alexandre III, one of the most beautiful bridges in the city, we could see across the river the huge dome of Ho tel des Invalides in the distance.

But the attention of the other passengers was directed at the long line forming outside the Grand Palais, where a collection of Rembrandts on loan from the Dutch was being shown. The bus nearly emptied here, but the show was just beginning for us. Soon we were at the edge of the Champs Elyse'es and then the Place de la Concorde. Paris opened up before us like a bloom.

Across the wide expanse of the Concorde, a sea of traffic encircled the Obelisk de Lougsor, and in the distance we could see the grand arcades along the Rue de Rivoli. Just ahead on the left was the Tuileries Garden, and across the river we could see the impressive Gare D'Orsay, partially covered in a latticework of scaffolding as work progressed on the building planners hope will become the third great art museum of the city when it opens this December. Down on the river, a low-slung working boat built to navigate under the ancient bridges of the Seine was making its way upstream toward the Ile de la Cite'.

Now there was just the driver at one end of the bus and us at the other as we approached the long roof of the Pavillon de Flore, the building that marks the beginning of the Louvre. We brushed by the south wing of the famous art museum for nearly a quarter of a mile until the "palace" finally gave way to the "museum" and the grand entrance at Place de Louvre. On the right, across the river and on the Ile de la Cite', we could see the Palais de Justice and the brooding medieval jail, the Conciergerie, where Marie Antoinette spent her last moments of life awaiting the guillotine. And suddenly there were the flying buttresses of Notre Dame.

Finally, sooner than we would have liked, the bus slowed and turned left in front of the Ho tel de Ville, the end of the line.

We got off the bus, slightly shaken by all that we had seen in just the last five minutes. It was like getting off a roller coaster. Then we set off amid the bustle of downtown Paris to continue our sightseeing on foot.

It was a short walk to Notre Dame and then on to the Left Bank. We spent the entire day exploring aimlessly, but with a feeling that we knew the layout of the city from our ride along the Seine.

It was growing dark as we headed back to the Ho tel de Ville, where we knew we could pick up the bus for the ride back home. We had seen enough for one day. But the 72 held one more surprise.

As the driver closed the doors with a hydraulic woosh and we began to roll through the crowded commercial district that lies between the Louvre and the Ho tel de Ville, we had assumed the bored, aimless gaze of the other passengers. There were no oohs and aahs.

The bus filled quickly, and passengers were standing in the aisle, obscuring our view. A few yellow headlights came on as we rolled down the Rue de Rivoli toward the Concorde, where the bus would hook back up with the river and retrace the route we had taken that morning.

I leaned over, pressing my face against the window, to catch a glimpse ahead, and I saw just a hint of what the 72 held in store: To our left the Concorde. Up the Rue Royale to the right, the Madeleine. A little further along on the right up the Champs Elyse'es, the Arc de Triomphe. And then the river.

The City of Lights!