Archaeologists have unearthed a 20-metre stretch of ancient wall beneath Paris, and France's culture ministry is calling it a "major breakthrough" - which, given the French, is probably the understatement of the century. The wall, dating from the Gallo-Roman period, was discovered this summer under a building on the Île de la Cité, conveniently located near Notre Dame Cathedral, because nothing in Paris can be discovered without a world-famous landmark looming nearby.

The stone-and-wood structure is believed to be part of the ramparts of Lutetia - the ancient name for Paris - built by the Gallic Parisii tribe, who lived along the River Seine during the Iron Age. So yes, the Parisii were essentially the original Parisians, presumably complaining about the price of wine and the lack of parking.

For years, historians have debated whether the Île de la Cité was the heart of Lutetia or whether the whole thing was actually in Nanterre, a suburb to the west. Nanterre's case has now suffered a serious blow, much like a Gaulish warrior facing Caesar's legions.

"We may be looking at one of the most important remains ever discovered for understanding Gallic Lutetia," said culture minister Catherine Pégard in a statement on Wednesday, adding the obligatory scientific caveat that they still need to verify its function and chronology - because nothing ruins a good archaeological buzz like peer review.

Lutetia was first mentioned in book seven of Julius Caesar's Gallic Wars, where it was described as being on an island in the River Seine. A vague description, sure, but it's not like Caesar had Google Maps.

The wall, found during excavations beneath the Hôtel-Dieu hospital, bears traces of fire. This could correspond to Caesar's account that the Gauls set fire to their town before the Battle of Lutetia against the Romans - a classic scorched-earth strategy, or perhaps just a really bad case of arson.

Carbon dating of the charred evidence places the find between 200BC and 10BC, a timeframe that neatly covers the Battle of Lutetia in 52BC. So the wall might have witnessed one of history's more forgettable battles, but hey, at least it survived to be dug up by archaeologists and turned into a press release.

The Île de la Cité is the largest island in the Seine in the Paris region and later became the centre of the Roman settlement of Lutetia. So if you've ever strolled along the Seine and thought, "This feels historically significant," congratulations, you were right - and also, you're standing on 2,000 years of rubble.