The historic center of Avignon is surrounded by a fortress wall built in the 14th century, with a total length of about 5 km with 39 towers and 8 gates. These walls are considered the longest defensive system in Europe. But the walls do not completely encircle the city, on the north side they rest against a rocky ledge, which is the natural defense of the city. A deep ditch filled with water was once dug around the walls. The bridges leading across the moat were raised at night, so it was impossible to get into the city at night.→