The simple white graphics on chocolate-coloured backgrounds will serve the same purpose for future archaeologists that illuminated manuscripts from the monasteries served for ours. OK, they'll be a little bulky, but what they lack in terms of convenience, they'll make up for in sheer eclectic flair. Whoever draws them is better at straight lines than curves and so future generations might look at the signs advertising seaside-towns and speculate that the beaches of France were once filled with square- shaped girls, their hair tied in triangular plaits, throwing a cube-shaped ball backwards and forwards.
You have to stare so hard at some of the signs to make out what they're supposed to be that they must have caused hundreds of accidents. The one that tells you you're passing the ancient town of Provins south of Paris looks like a large-scale illustration of an engine part from a motoring manual. It's only when you're so close that your passenger could reach out of the window and strike a match on the sign that you realise that it's actually a small-scale drawing of a perfectly preserved medieval monastery.
Many noticeboards owe more to municipal pride and commercial optimism than to any realistic hope of boosting tourism. You drive past some towns in northern France that proudly proclaim the presence of petrochemical plants. It's hard to imagine hot, grumpy children being calmed on the long drive south by the promise that Daddy will turn off the motorway so we can see where that funny smell of sulphur is coming from.
My own favourite probably doesn't attract many visitors, either. It advertises a nuclear power station on the main road from Paris up into Normandy. A pity, really, since the adjoining picnic area commands rather a nice view of the building that houses the main reactor. When I was young I used to imagine that the towns with only lousy attributes such as agricultural machinery factories to trumpet would feel like the sort of kids who never got picked when we were making up football teams at school, and I'd feel sorry for them.
Equipped then with a limited grasp of the feelings of the provincial French towards outsiders in general and foreigners in particular, I used to imagine myself explaining to a small crowd of grateful locals just why we'd chosen to visit the town. Luckily, I never found out what would really have happened since no one I ever travelled with actually agreed to stop at one.
You can see, though, why local government officials think it's worth trying to treat whatever happens to be near the town as a tourist attraction. After all, France has become one of the most visited countries in the world. British visitors arriving through the Channel ports join a tidal wave of holidaymakers from northern Europe journeying towards the sun.
It is a sign of progress that where once military look-outs stood on the high ground above the Channel and charted the progress of ships bringing the bowmen to fight at Crecy or Agincourt, these days there are spotters calculating nothing more lethal than the state of play in the great war between the ferry operators, hovercraft-owners and tunnel shareholders vying for the business of bringing people across from Britain on to the island of mainland Europe.
The crusaders came this way in the 11th century, stopping at churches all the way through France on their way to the Holy Land. There are still places in central France where a day's march took the traveller from one hill-top church to another on the way south. These were hot, wearying days, punctuated by visits to shrines that were supposed to contain the bones of the saints.
The 19th century brought the British navvies who built the railways of northern France. They awed the locals with their appetite for hard work, beef and beer, acquiring a reputation whose only modern parallel would be a combination of English soccer hooligan and Japanese car-worker. Above all, soldiers have come this way and left their mark. Near Boulogne you can visit the graves of soldiers of Napoleon's army who died of sickness and, they used to joke, old-age, waiting for the great man to make up his mind about the best way to invade southern England.
In the other direction has come a ceaseless tide of invasion, occupation and liberation. I am the of the first generation of my family this century to make his first visit to Europe equipped with a bucket and spade, rather than a rifle and pack.
This is an extract from the first programme in Kevin Connolly's series on Radio 4, 'Going South', which begins tomorrow at 8.45pm.Reuse content