Input (grade 13): Some undemolished remains of one tower of the fort were discovered during excavation for the Métro (rail mass-transit system) in 1899, and were moved to a park (the Square Henri-Galli) a few hundred meters away, where they are displayed today.
Output (grade 8): The remains of one tower of the fort were found during digging for the Métro (rail mass-transit system) in 1899.