Cathedral of Saint Étienne, Paris

The paved square known as the Parvis Notre-Dame holds the silent foundations of a vanished history. Beneath your feet lies the footprint of the Cathedral of Saint Étienne, an early Christian church that occupied this island as early as the fourth or fifth century. While nothing of the structure remains above ground today, this site functioned for centuries as the primary cathedral for the city, housing mosaics and antique columns salvaged from Roman foundations.