About forty kilometers from Paris, the two towers of the Notre-Dame collegiate church overlook the Seine and the rooftops of Mantes-la-Jolie. Measuring nearly 68 meters in length, with a nave rising to almost 30 meters and towers exceeding 54 meters, the building’s dimensions are more typical of a cathedral than a collegiate church. Its resemblance to Notre-Dame de Paris has earned it the nickname “Notre-Dame’s little sister.”
And the resemblance is not merely aesthetic. Construction began around 1150, just as major Gothic projects were beginning to transform the Île-de-France region. Its twin-tower façade, its three-level interior elevation, and its six-part vaults are directly reminiscent of several great 12th-century cathedrals, notably those in Paris, Laon, and Senlis.
The Collegiate Church of Mantes-la-Jolie, one of the great Gothic monuments of Île-de-France
Inside, the nave rises over three levels, featuring large arches, galleries, and tall windows. Unlike many medieval buildings that have been profoundly altered over the centuries, the collegiate church still retains a significant portion of its original structure.
This is particularly true of its medieval roof structure, which is comparable in design to that of Notre-Dame de Paris before the 2019 fire. The building has also preserved three large portals, an imposing western rose window, and several elements characteristic of early Gothic architecture.
Yet its history could have come to an end on several occasions. The Revolution led to looting and damage, before the collegiate church was included on the first list of French Historic Monuments in 1840. A lengthy restoration carried out in the 19th century made it possible, in particular, to restore the façade and rebuild the north tower.
The building then weathered a particularly dramatic episode in 1944. Bombing raids destroyed a significant portion of downtown Mantes and its bridges, but the structure of the collegiate church remained standing. Several doorways and stained-glass windows were damaged. The large rose window on the façade, however, escaped the disaster: its stained-glass panes had been removed before the bombings and stored safely in a cellar in the Martraits neighborhood.
A medieval site easily accessible from Paris
The collegiate church continues to undergo a major restoration program today, particularly involving its flying buttresses, apse, and towers. It can now also be viewed in a much more unusual way: since August 2026, a complete 3D scan has made it possible to virtually explore the monument and observe certain details that are normally difficult to access.
The collegiate church is located in the heart of the historic center, just a few meters from the Seine and the Hôtel-Dieu Museum. Guided tours focusing on its architecture and history are also offered throughout the year.
Location: Notre-Dame Collegiate Church, Place de l’Étape, 78200 Mantes-la-Jolie
Hours: Open daily; guided tours offered by the Heritage Department according to the schedule.