Monte Sainte Victoire, immortalised in many paintings by Cezanne, is a massive, 12-mile long, limestone ridge, which straddles two French departements. Plans to build a new motorway from Paris to Nice threaten to desecrate the iconic countryside. (0730156)

IT’S the UK’s biggest show of exclusively Picasso paintings for half a century and yet its opening last week at the National Gallery in London attracted devastating criticism from serious art commentators.

Billed as a blockbuster following a similar exhibition in Paris, Picasso: Challenging the Past was described by the Financial Times as ‘a travesty’: The Independent asked ‘Why on earth has the National Gallery gone down the tired route of linking him to the old masters?’ and The Guardian announced ‘Picasso in London is a disappointment’.

Even so, it seems most unlikely that the thousands of his followers will be deterred from going to the exhibition which runs from now until June.

After all, Pablo Picasso was arguably the most important and influential artist of the last century.

Picasso himself was a passionate admirer of other European artists such as El Greco, Velazquez and Goya and he was particularly influenced by Cezanne, acknowledged as the ‘father of modern art’.

‘My one and only master’, was how Picasso described the French post-impressionist.

By coincidence or design (and I haven’t discovered which), a Cezanne exhibition also opened across the Atlantic last week at the Philadelphia Museum of Art.

‘Cezanne and Beyond’ includes 50 works by Cezanne drawn from private and public collections all over the world and it’s taken 10 years to put it together.

Such is his popularity in the United States that the last time the Philadelphia Museum held a Cezanne exhibition, the organisers calculated it pumped nearly £100m. into the city’s economy.

The link between Cezanne and Picasso is so strong that the city where Cezanne lived, Aix-en- Provence in the south of France, is bringing together these two great artists in an exhibition of its own, to run from May until September.

Picasso was influenced to such an extent by Cezanne that he bought Chateau Vauvenargues and 2,500 acres of land at the foot of Mont Sainte-Victoire, the mountain near Aix, which Cezanne immortalised in no fewer than 87 separate canvases.

‘I have just bought myself Cezanne’s mountains,’ Picasso told his agent after completing the deal.

Picasso died 35 years ago at the age of 91 and was buried in the grounds of the chateau.

To coincide with the Aix-en- Provence exhibition, the chateau and grounds are to be opened to the public for the first time.

Cezanne’s painted impressions of Provence and Monte Sainte Victoire have made the surrounding countryside powerfully symbolic of France. (0733408)

So, how could this coming together of two of the greatest exponents of modern art in one exhibition find itself overshadowed by the mother of all planning disputes? Thousands of holidaymakers driving to the south of France along the ‘autoroute du soleil’ have their attention drawn to the massive Mont Sainte Victoire.

It’s easy to see how Cezanne was mesmerised by this mighty limestone ridge, stretching for 12 miles and straddling two French departements, the Bouches du Rhone and the Var.

Even though high-speed TGV railway lines and motorways have been carved into the countryside across parts of southern France, Mont Sainte Victoire and its foreland has mostly been spared desecration and remains in all its mindbending glory for everyone to admire.

However, at the very time when the Aix-en-Provence exhibition of the two greats is at its height, 30 June, a decision will be announced for a new route which will take high-speed trains from Paris to Nice: it’s a decision that had been expected last month but was postponed after local delegations had met the ecology minister in Paris.

The new line is set to open by 2020 and two routing possibilities are under consideration.

The quickest, the northern route, would reduce the Paris-Nice journey to a staggering four hours.

Apart from benefits to tourism and industry in the Cote d’Azur region, the new fast line would also boost efforts being made by the Mayor of Nice to host the 2018 Winter Olympics.

To achieve this fast route, though, a swathe would have to be cut through the arrière pays at the foot of Mont Sainte Victoire – a swathe that Cezanne’s successors angrily describe as a ‘bloody sword stroke’.

Philippe Cezanne, the artist’s great-grandson, says he feels under attack.

‘The soul of Cezanne is in these hills,’ he says.

‘It’s still quite magical and all the foreigners who come to the region are surprised to find the landscapes as the artist found them.’ The alternative, the southern route, would take the new line along the coast through the coastal cities of Toulon and Marseille.

Not only would it add 20 minutes to the journey to Nice, it would be £3bn more expensive.

The Mayor of Aix, firmly against the route around Mont Sainte Victoire, led noisy booing directed at the Mayor of Nice outside the environment department in Paris when recent discussions were held there.

Central government appears to be wavering and worrying.

President Sarkozy himself indicated last year that he was in favour of the southern route but local politicians now claim ministers are looking more favourably at the cheaper northern route.

The French love big building projects and are proud of their road and rail network.

Unlike in Britain, where planning processes can hold up work for years, the French are well known for going ahead and holding any planning enquiries after the deed has been done.

Remember Clochemerle? Never very good at laughing at itself, France was, nevertheless, as amused by Clochemerle as anybody else.

The famous satirical novel was set in a fictional Beaujolais village and catalogued the ramifications of a plan to build a gents’ lavatory in the market square.

The row, though, in Provence is something else.

Thousands of Aix-en-Provence protesters have already demonstrated their opposition to the northern route at the city’s TGV station, waving banners which read ‘Saint Victoire, you will tremble’ and ‘Help, Cezanne, they have gone crazy’.

By the end of June, it’s usually pretty hot in the Provence region.

This year, tempers are likely to rise with the temperatures.