Archaeological Crypt of the Île de la Cité
Visitor Information
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Official Website: www.crypte.paris.fr
Country: France
Civilization: Roman
Remains: Civic
History
The Archaeological Crypt of the Île de la Cité is located in Paris, France, beneath the square in front of Notre-Dame Cathedral on the Île de la Cité, an island in the Seine River. This site preserves layers of the city’s history from the Roman period through the 19th century. The original settlement, known as Lutetia, was established by the Gauls and later developed under Roman rule.
During the Roman era, beginning in the Augustan period (late 1st century BCE to early 1st century CE), the small islands in the Seine were unified to form the Île de la Cité. Lutetia grew into a significant urban center with public buildings and defensive structures. In the 3rd to 5th centuries, the city faced Germanic invasions, prompting the construction of a fortified city wall to protect its inhabitants.
The medieval period saw the Île de la Cité evolve around the construction of Notre-Dame Cathedral, which began in 1163. The island became a religious and administrative center, with houses, chapels, and hospitals developing in its vicinity. Several churches, including Saint-Christophe and Sainte-Geneviève des Ardents, were established but later destroyed.
In the 18th century, the island underwent major changes. Medieval buildings were demolished to make way for new institutions such as the Hospice des Enfants-Trouvés, built in 1750. The Sainte-Agnès chapel survived a fire in 1772 that destroyed much of the medieval Hôtel-Dieu hospital.
The 19th century brought further transformation under Napoleon III’s urban renewal program led by Baron Haussmann. This modernization included the removal of many medieval structures, the construction of new buildings like a police barracks, and the installation of modern sewer systems. These changes reshaped the island’s layout and infrastructure.
Archaeological excavations began in 1962 under Michel Fleury and continued until 1988, uncovering the site’s rich history. The crypt was established as a museum in 1980 to preserve these remains. It closed temporarily after the 2019 Notre-Dame fire and reopened in 2021. A redevelopment project for the crypt’s entrance and surroundings is planned for 2024–2027.
Remains
The crypt covers an area of 2,200 square meters, extending 118 meters long and 29 meters wide, with 1,800 square meters dedicated to exhibitions. It displays archaeological layers from Roman times through the 19th century.
Among the oldest remains is a segment of the ancient Lutetian port quay wall, built to support river trade. Nearby lies a Gallo-Roman public bathhouse featuring a hypocaust system, an ancient underfloor heating method using hot air circulation. This bathhouse illustrates Roman urban amenities.
A portion of the 4th-century city wall is preserved, constructed from large stone blocks taken from older necropolises and abandoned monuments. This defensive structure reflects the city’s response to external threats during late antiquity.
Medieval remains include the basement of the former chapel of the Hôtel-Dieu hospital and foundations of houses along Rue Neuve-Notre-Dame. Foundations of two destroyed churches, Saint-Christophe and Sainte-Geneviève des Ardents, are also visible, marking the island’s religious heritage.
From the 18th century, the crypt contains the foundations of the Hospice des Enfants-Trouvés, designed by architect Boffrand in 1750. The crypt of the Sainte-Agnès chapel, which survived the 1772 fire, is also preserved.
The 19th-century layer reveals Haussmann-era sewers and evidence of urban restructuring, including the removal of medieval alleys and churches. New constructions such as a police barracks replaced earlier buildings.
The crypt’s current entrance is located on the western side of the parvis near parking access, designed in a discreet modern style. Plans are underway to create a new entrance integrated with the former parking area.
Archaeological finds include large stone blocks and column bases from Roman houses, illustrating the city’s evolution from Roman Lutetia through medieval and modern periods.
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