When the French look back today, they generally trace the stirrings of national glory to François I in the mid-16th century or perhaps to Louis XIV 150 years later. And when Parisians look around, they see mainly the city reshaped into broad avenues by Baron Georges-Eugène Haussmann in the 19th century.

This week, they were reminded of a far earlier Paris, one that was still called Lutetia. On a Left Bank hillside, which carries the name of Sainte-Geneviève, the patron saint of Paris, French archaeologists have found remnants of a road and several houses dating back some 2,000 years to when Rome ruled Gaul.

In one sense, it was not a surprise. Other Roman vestiges have been uncovered, notably those of a theater that could seat 15,000 and Roman thermal baths found beneath the 15th-century Abbey of Cluny.

Yet the area of the new find, half a mile to the south, was so heavily built up in the early 20th century that it is hard to imagine space for excavation.

In this case, however, the Pierre and Marie Curie University decided to replace a temporary structure with a research building. And, by law, construction in central Paris cannot begin until archaeologists have had a chance to investigate.

They started digging in early March and almost immediately made one of their best finds in recent years.

As it happens, the Convent of the Visitation covered the 4,400-square-foot plot from the early 17th century until 1910, when it was demolished. One long-buried wall of the convent has been uncovered. Further, the site is crossed by a large drainage pipe, confirmation that interest in preserving ancient ruins is fairly new.

However, now quite visible is a 20-foot-wide road, as well as the walls and floors of at least three houses. In one house, archaeologists have been able to identify an under-the-floor thermal heating system. And across the site, coins and ceramic shards have been found.

Further, this area was inhabited long enough for stone walls to replace earlier adobelike clay-and-wood building material.

The significance of such finds, of course, is what they reveal about earlier times. It is known that early settlers around the Île de la Cité burned their houses before they were conquered by a Roman legion under Labienus in 52 B.C. But in the decades that followed, a new town was built on the Left Bank, which eventually had a population of 12,000 to 20,000.

Then, after the first barbarian incursions in A.D. 253, the population apparently withdrew from the hill of Sainte-Geneviève and sought refuge behind new walls on the Île de la Cité, which was called Paris, borrowing the name of the ancient Gallic Parisii tribe. Thus, because the archaeologists have found no traces of occupation of the site between the 4th and 17th centuries, they have been able to confirm that even an area little more than a mile from the Seine was long considered insecure for habitation.

"It was a neighborhood of the Augustan period," explained Didier Busson, the architect in charge of the dig. "It may have been founded by Gauls who had been in the Roman army and settled here, bringing with them their experience of building."

Today, the Rue Saint-Jacques follows the path of the Cardo Maximus, the north-south road that crossed the district.

Still, for all the attention stirred by this find, archaeologists have only until late June to complete their studies because, after that, construction will begin on the site. But Mr. Busson is nonetheless satisfied with what has been achieved.

"Thirty years ago, this site would have been destroyed even before we had a chance to excavate it," he said. "Maybe in 20 years it will be possible to preserve things as we find them."