One of the most venerable and adored old ladies in the world – the 13th- century cathedral at Chartres, south of Paris – is undergoing a dramatic facelift.
When the first "bandages" are removed later this year, the effect will be startling, and could be deeply controversial. Imagine how you might feel if your great, great, great grand-mother was suddenly made to appear 20 years old again.
The interior of one of the most beautiful and most visited of all Gothic cathedrals, now grey and leprous with 800 years of whitewash, paint and grime, is being gradually returned to its medieval condition. This is not a repaint but, in the case of 80 per cent of the walls and roofs, a restoration of the original 13th century décor, rediscovered only 20 years ago under the dirt and mistakes of the centuries.
No other Gothic cathedral has retained, accidentally, so much of its original painting. When the work is complete in five years' time, Chartres will be the first cathedral interior to be returned to the way it looked when consecrated, in 1260.
Judging by an advance viewing, the effect will be stunning. The dingy interior – deplored by some, regarded as part of its ancient mystery and charm by others – is being transformed into something gleamingly bright and ethereal.
We scrambled through the scaffolding, high up into the choir 200 feet above the ground, to see the progress on the first stage of the restoration, which is to be unveiled just before Christmas. Conservation experts have stripped away the patina of the centuries to uncover a pale ochre wash, brushed on to the walls when the cathedral was constructed between 1194 and 1225. Still almost complete is the original white pattern of "fake" stone joints, which do not follow the lines of the real masonry. They were painted on to give the walls a more uniform look.
The soaring arches, ribs and columns – the vaulting which made the immense Gothic cathedrals possible – have been scrubbed from their unsavoury, deep grey to the original bony white. The elaborately carved keystones which hold the vaulted roofs together have been repainted to a gleaming red, green, black and gold, based on the fragments of medieval colour which have survived.
With €6m of European, French state and local government funding, work will begin on other parts of the cathedral next year, and should be complete by 2014.
"You could say that we are taking a risk by transforming something which is admired and loved by so many people," said Gilles Fresson, the historian overseeing the work for the rectorate of Chartres cathedral. "But you could also say that we are putting our trust in the people who first conceived this beautiful place.
"People sometimes think of Gothic architecture as dark and sombre, but that is not the way that the original architects and masons saw their work. Cathedrals were originally intended as a way of gaining a glimpse of paradise on earth. They were designed to be ethereal buildings, temples of light."
Chartres is already unique in several ways. It was completed in just 30 years. Unlike most other cathedrals, it has never been extensively rebuilt, and has retained 80 per cent of its original stained glass. It emerged in 1989 that, unlike any other Gothic cathedral, the original medieval internal décor had been preserved beneath layers of 19th-century white-wash and grime.
"The medieval cathedral-builders intended their work as a unified whole, " Mr Fresson said. "The exterior, the stained-glass, the statuary all played a part. We now also know that the original builders intended the interior to have pale walls and whitened columns."
Mr Fresson expects some visitors to Chartres to be taken aback – maybe even angered – by the transformation. "There is no doubt that we will lose something, even if we gain a great deal," he said. "The sense of mystery, the sense of the passing ages, which you receive when you enter the dark interior of today will be replaced by something fresher and much more dynamic."
Concerns have been expressed, in particular, about the effect of the restoration on Chartre's exquisite stained-glass windows: the most complete, and to many people the most beautiful anywhere in the world. The glass is also being gradually restored, largely with money raised by charitable appeals
"You could argue that the power of the windows has been increased by the cathedral's dark interior and that their beauty will therefore suffer," said Mr Fresson. "Our first impression, from the work so far, is that the effect will be different, but no less beautiful."
Within their new white surroundings, the "rose", or large circular windows, are even more dramatic, he said. The vertical upper windows stand out against the pale ochre of the walls.
In the darkened, unrestored interior, the windows shine like individual jewels, he said. In the section under restoration, Mr Fresson said, "you feel that you are in a shower of light and colour, as if you were bathing in an atmosphere gleaming with all the colours of the windows at once. The cathedral becomes an ensemble again, as the medieval creators intended."
If anyone could be expected to mourn the "loss" of the old dark interior of Chartres, it might be Malcolm Miller. He came to the cathedral as a temporary student guide from Sutton Coldfield in the 1950s, and has gone on to become the greatest single authority on Chartres, and – as he says himself – "part of the fabric of the cathedral".
Aged 75, decorated by the French state, he still gives his cathedral tours in English twice a day (except Sundays). "People ask if I get bored after half a century, but how could you get bored with this wonderful building, " he said. "I still learn new things about it every day."
What does Mr Miller think about the transformation – or resurrection – of the interior of the cathedral which has been his life's work? "I am delighted. Excited. I can't wait to see it finished," he said. "My mother lived on into her nineties so I must have some chance of surviving for another five years."
To Malcolm Miller, the restoration of the interior of Chartres cathedral is not a sacrilege or a risk, but a triumphant return to authenticity. "All medieval cathedrals were painted inside," he said. "They were like Roman or Greek or Egyptian temples. We have come to think of them as unadorned or austere places, but that is not the way that they were intended to be."
With the help of a powerful torch, he took us on a tour of the darkened recesses of the cathedral, pointing the beam at the still unrestored key-stones high in the roof, picking out the tiny flecks of medieval colour which still remain. He also took us to see a recently restored group of 13th-century statues above the western door of the building. Here too, the recent removal of centuries of grime has shown that, as long suspected, the statues adorning the exterior of Gothic cathedrals were once brightly painted. Scraps of blue, black and green have reappeared on the cloaks or faces of the biblical figures. Entire statues have been shown to be not plain stone but dyed in the same ochre "sizing", or wash, as the interior walls.
"Of course, some people will complain when the interior is restored," Mr Miller said. "People always complain. They complained when these statues were restored. They complained when Rembrandt's Night Watch was restored and turned out not to be an image of the Night Watch at all. Personally, I can't wait until the inside of the cathedral is cleaner and brighter. We know that that was how it was meant to be. Why should it not be that way again?"
Chartres cathedral: A brief history
*The cathedral at Chartres was among the first sites to be included in the Unesco list of world heritage in 1979. It is regarded as one of the great masterpieces of Gothic architecture.
*Chartres was the first cathedral to use flying buttresses extensively. At the time of its building, it had the tallest roof in the Western world (about 38 metres).
*Unlike most medieval cathedrals, Chartres was rapidly completed to a single plan in the early 13th century. Unlike almost all other medieval cathedrals, it has never been significantly rebuilt or extended (other than its 16th century second spire). Its 176 original stained glass windows are the most complete set of medieval stained glass in the world.
*The cathedral is believed to be the fifth on the site. The town of Chartres, 50 miles south-west of Paris, was one of the great centres of medieval learning, long before universities were created. In the 10th century, it became, and still is, an important place of Catholic pilgrimage with the acquisition of a biblical relic: a "veil" said to have been worn by Mary during the birth of Jesus.