Archaeologists uncover 22-metre Gallic wall beneath Île de la Cité in Paris

Excavations beneath the Hôtel-Dieu

Archaeologists excavating beneath the Hôtel-Dieu hospital on Paris's Île de la Cité have uncovered a 22-metre section of a stone and timber rampart. The excavations began in February 2026 across two courtyards of the hospital complex, overseen by the City of Paris Archaeological Service (DHAAP) and the National Institute for Preventive Archaeological Research (Inrap). The work was commissioned by the Regional Directorate of Cultural Affairs in Île-de-France during a restructuring project managed by the Paris Public Hospital Authority (AP-HP). Situated four metres below the surface, the structure rests next to Notre-Dame Cathedral in the central district of the capital.

Paris Mayor Emmanuel Grégoire presented the discovery on Wednesday alongside cultural officials.

It is the greatest archaeological discovery in the history of Paris, the trace of Lutetia before the Roman invasion, described by Julius Caesar in The Gallic Wars.

Rampart construction and burned remains

The excavated fortification combines stone blocks with horizontal and perpendicular wooden beams, a technique characteristic of late Iron Age Gallic oppida. Measuring approximately 22 metres in length, one metre in height, and two metres in thickness, the wall was reinforced on its inner side by an artificial platform of sand and gravel nearly two metres thick. Excavation teams also recovered a Gallic spearhead and a coin near the base of the wall.

The wall features visible burn marks across its stone cladding, accompanied by charred seeds and the remnants of a burned wooden building situated directly in front of the masonry. Initial radiocarbon testing of the preserved timber elements yielded a date range between 200 BC and 10 BC. This chronological window encompasses the 52 BC Battle of Lutetia, where, according to Roman accounts, the Gallic Parisii tribe set fire to their settlement to deny it to advancing Roman legions under Julius Caesar.

Debating the original site of Lutetia

The discovery addresses a long-standing historical debate concerning the geographical cradle of Paris. In his Gallic Wars commentary, Julius Caesar described Lutetia as an island settlement situated in a bend of the River Seine, connected to the mainland by bridges. Because conclusive material evidence on the Île de la Cité had been lacking, several archaeologists had previously argued that Gallic Lutetia was located in modern-day Nanterre, a western suburb of Paris where substantial late Iron Age remains were identified.

French Minister of Culture Catherine Pégard stated that while the findings provide compelling evidence for an Île de la Cité settlement, additional analysis is planned to establish the site's complete layout.

We may be looking at one of the most important remains ever discovered for understanding Gallic Lutetia. Scientific caution still requires that we verify its function and its chronology, but the convergence of evidence is particularly remarkable at this stage.

Next stages of archaeological analysis

Specialists from Inrap and the municipal archaeology service will continue stratigraphic excavations and laboratory testing to confirm the exact function of the wall. Researchers plan further dendrochronological and radiocarbon analyses of the charred timber samples to determine whether the fire coincided precisely with the events of 52 BC. The findings will be integrated into research documenting the transition from Gallic tribal settlements to the later Roman urban centre that expanded across the Île de la Cité and the left bank of the Seine during the first century AD.