You should generally allow 8 hours on foot or 3 hours on a mountain bike to make the journey from Lourdes to Pau. The itinerary is signposted with blue and white painted markings. There are additional blue direction signs at some intersections or heritage sites in order to ensure that walkers go in the right direction. They give walking times between certain sites and villages.
In spite of its name “Chemin Henri IV”, this trail does not seem to have anything to do with King Henry IV. Its original path seems to correspond to a Roman road connecting Lourdes to Lescar (a town near Pau), thus avoiding the marshy plain that was there at the time. Used in Antiquity and the Middle Ages, it is dotted with many relics from those periods: these include Caesar’s Fort near to the hamlet of Ousse, and a Roman camp near Mourle Forest. There are also signs of earlier human activity there, with tumulus and dolmens in evidence all along the trail (Peyre Dusets dolmen).
Literature available at the Tourist Office