The strongly fortified historic centre of Briançon, with its narrow roads, was built in the 17th Century near the confluence of the Durance and Guisane rivers, approx. 100 m higher than the valley bottom which is now occupied by the modern part of the town. The purpose of the fortifcations, planned by Vauban, was to protect the region from the Austrians. Note the open drainage channel in the middle of the road.