Part of the pleasure of the annual telecast of the Tour de France is the travelogue element as the helicopter camera veers away from the peleton to soar over the surrounding countryside.
This year they have passed over a couple of lesser known architectural gems of the eastern part of France close to the Swiss border.
No more than 100km apart, they are separated by 180 years but are each the masterworks of uniquely visionary architects.
The first is the Royal Saltworks, at Arc-et-Senans. It seems extraordinary that this group of magnificent buildings was constructed for the production of what today is a cheap, everyday commodity. But in the early 18th century salt was known as white gold. It was widely used for preserving food and was a good earner for the king thanks to a tax called the gabelle, which was to became one of the triggers of the French revolution.I'm approaching from the south having driven from Lyon, leaving the motorway, then plunging into the verdant and hilly Jura region. This is classic Tour de France country with rolling countryside and gorgeous stone villages.
The road flattens out and, after a dead straight section of what was clearly once the driveway, I arrive at an imposing Doric-columned portico, the gatehouse of the Saline Royale.
Built in the 1770s, the complex is laid-out on a symmetrical semi-circular plan which was to form the centre of an ideal neoclassical city, the embodiment of the utopian ideas of the Enlightenment. The centrepiece is the Director's House, and around it are the various workshops, stables and workers' housing. Behind are kitchen gardens which supplied food for the community. A high wall surrounds the whole lot, but the rest of the city was never built.
The works lay abandoned for many years, miraculously surviving attempts to demolish them and being used as a prison camp for gypsies during World War II.Restoration began in the 1960s and the site won UNESCO World Heritage listing in 1982. Today, the Director's House contains a museum of the history of salt, while another building houses one dedicated to the architect of the saltworks, Claude Ledoux.
Ledoux was a fascinating character whose idiosyncratic take on classical building has made him a hero to successive generations of architects. Extraordinary projects for buildings like giant pyramids or spheres were largely unbuilt, especially after the revolution found him unfortunately lumped in with the ancien regime.
One of the architects influenced by Ledoux was the great modernist Le Corbusier, born not far away in La Chaux-de-Fonds in Switzerland. His masterwork is near the town of Belfort which Le Tour is also visiting this year.
Setting out on a cold grey day I can see my destination from miles away, sitting on top of a hill above the village of Ronchamp.
Looking like a giant mushroom sprouting among the trees, Notre Dame du Haut calls to the faithful, who these days are more likely to be of the design variety than the divine.
When it was built in 1955 it confounded the architectural world in a way similar to Bob Dylan plugging in his electric guitar a decade later. Corbusier was seen as the high priest of the pure white cube approach to building, the "poet of the right angle". So this wildly amorphous, organic, sculptural object which seemed to defy rationality was shocking in the extreme.
Now it has become something of a sacred site in its own right and, seen in the light of Corbusier's subsequent buildings, is perhaps a little easier to read.
As a pilgrimage church, one is supposed to climb the long, steep, muddy path on foot to fully appreciate the experience. However, on this drizzling windy day I'm glad of the new visitor centre with its generous car park. Not that there are many punters today. So I have the place to myself for a while.
But once up the hill, the magic is palpable. Inside the cave-like interior the feeling is not really like a church, more like some kind of much older animist sacred space. The trappings of Catholicism, the altar, the candles, the cross, seem like afterthoughts.
Nothing is symmetrical, none of the walls are straight, the ceiling is a rolled grey wave. Even the floor drops away following the curve of the top of the hill. You are aware mostly of light. The falling light down the high chimney towers above the three rounded chapels within the church. The slivers of light where the ceiling seems to hover above the walls.
But mostly the magical south wall with its deeply chamfered openings, some tiny, some big enough to walk into, tapering to coloured, painted, and clear glass windows.
For an atheist who has long waited to see this place it is almost a religious experience. Even on this freezing cold day it has a powerful aura.
• Check the opening times, because it is closed at lunchtime in the off season.