This is the area where the four major pilgrim routes that traverse Europe, northeast to southwest, converge into the Camino de Santiago - the Way of St James - which wends its way between the mountains of northern Spain to the place that bears his name and where it is said his remains are interred.
In St Jean, there is a visitor centre for pilgrims. It is in the old town, inside the citadel on a steep, narrow cobbled street.
There are maps on the walls, photographs and various notices. Behind three tables sit three helpers who take their role very seriously and are only interested in genuine pilgrims.
They are jealous guardians of the integrity of the Camino - tourist-type queries are waved in the direction of the tourist office.
A visitor book holds messages from pilgrims in a variety of languages - French, Spanish, German, Dutch, Korean, Japanese and English.
The messages are generally of a piece: "My pilgrimage begins," is a popular one; "finally here" is another; "wish you all an enlightening experience," says another; "I hope you find what you are looking for," wrote Rachel from the US. "Nothing is impossible," wrote Bridgid and Damian, the final message when Tony and I examined the ledger.
Outside back in the modern town, our bikes have attracted attention. "Nice machines," says another biker from Kent. "BMW. Hmmm, ideal for touring."
His bike is a vast red and chrome Harley-Davidson, a machine almost the width of a car. It has a fat, wide low-slung seat and half-moon shaped handlebars that can only be grasped with outstretched arms.
The bike is really an armchair on wheels. On the exhaust pipe, there's a statuette of an impressively curvaceous naked woman lying outstretched. The inspiration for this could well be the female getting off another Harley, his companion apparently.
The road over the mountains rises from St Jean like a corkscrew, twisting and turning right and left every few hundred metres. It is almost impossible to get out of fourth gear but a pleasure to drive. "If there's a heaven, I hope there's bikes like these and roads like those," says Tony.
At the top and through the Cize Pass, Spain unfolds 1,000m below. Here for the first time since leaving Vézelay in central France, we see pilgrims in abundance. They are walking along a path kept clear by the sheer numbers using it but someone has also gone to the trouble of cutting back growth on either side.
A little further on is Roncesvalles, a large monastic settlement with a modest-sized collegiate church, open to the public.
The inside is in almost total darkness. A young man is sitting in silence in deep contemplation of the altar, behind which is a representation of the 12 Apostles, Joseph and Mary and, on top, Jesus.
The silence is broken when a couple enter, put money into a slot machine and cause the lighting system to burst into life.
They set up a tripod in the nave and start taking flash photographs from all angles. The young man exudes stoical indifference to this insensitivity.
There's an extraordinary photograph in a nearby cafe. It looks like it was taken in the 1930s or perhaps 1940s.
It is a view down a tree-lined street in winter, on either side of which are walking two rows of young male religious.
Strapped to the back of each man is what looks like a tree trunk with a cross-piece on to which their arms are strapped. Why would a person inflict such discomfort - pain surely - on themselves as a totem of zealous devotion? And is the difference between this and the way Shia Muslims flagellate themselves and draw blood only one of degree?
The road from Roncesvalles drops down to Pamplona and west to Logroño and Burgos, through Navarre and Rioja.
The land here is flat and dull but with mountains in the distance north and south. Cereal crops are grown on almost every piece of land visible from the road.
Not far from the modern road is the 1,000-year-old Camino, linking a necklace of pilgrim refugios, places of food and rest for the walkers stretching over 700 km from Roncesvalles to Santiago.
We take a detour north, into the mountains to a place named Oña, a small town discovered some years ago by my research assistant, Sancho Panza. The Hostal Once Brutos has single rooms for as little as €15 a night.
The Sidreria Bar La Terraza nearby does everything possible to deter customers. Its formica-clad interior is filled with ghastly Pepsi-cola-supplied plastic chairs. A deranged man who chainsmokes inflicts himself incoherently on all comers.
And then we have a meal of squid in garlic and butter - deep fried squid, octopus and then steak. Cooked perfectly, served with cheer and washed down with rioja served in the local fashion - ice cold. The Once Brutos and La Terraza will never make it into a tourist guide. More's the pity.
Next:Burgos cathedral and vespers with the Benedictine monks; and an Irish pilgrim