Pont-en-Royans is situated in the mountainous region of the Vercors of the Rhone-Alps at the confluence of two rivers, the Vernaison and Bourne. The torrential meeting of these rivers necessitated the high location of the buildings.  It also created at a controlled access historically to the Vercors across this bridge. At one time there were three castles guarding access.  The road from here to Grenoble is very picturesque with a passage under overhanging rocks along a meandering rocky stream many feet below.  The road is barely wide enough for a even a single car in some areas much less for a tour bus.