To your right, a large arterial road heads into a hollow. It follows the initial course of the River Louve, which is now buried, but which over time hollowed out a valley in this spot. Together with its “cousin”, the Flon, this river created the Cité hillside by eroding the molasse, a grey rock used to build St. Maire Castle and the cathedral. Go from the castle courtyard to the cathedral. 5 mins.