The Crypte archéologique de l'île de la Cité is an archaeological crypt located under the Notre Dame Cathedral in Paris. The Crypt was opened to the public in 1980. The square where the Cathedral of Notre-Dame is located has seen many events unfold from the foundation of the city of Lutetia (ancient name of the city of Paris) in Roman times, up to the nineteenth. century, when many of the buildings and streets that obstructed the view of the Cathedral were demolished. The Crypt therefore allows you to observe a series of finds from different eras, such as the walls built to defend the city from the advance of the Gauls between the third and fourth centuries. In addition, the remains of a thermal plant and some buildings have also emerged. As for the medieval period, the remains of an ancient road emerged, built to facilitate the construction of the Cathedral, and later eliminated. In addition, the remains of an orphanage have also emerged, the Hospice des Enfants Retrouvées, an imposing building that occupied a large part of the square.