The moving of the Mona Lisa

This Wednesday, amid huge fanfare, the Mona Lisa is to be unveiled in her new home in the Louvre. John Lichfield asks what makes this painting the most visited, most written about, most sung about, most parodied work of art in the world

Next week a wooden object 502 years old, inventory number 779, will be moved to a new location in the largest art museum in the world. The object is a small portrait of an obscure Florentine gentlewoman, painted on a thin panel of poplar. It is known to most of humanity - but not to France or Italy - as the Mona Lisa.

Next week a wooden object 502 years old, inventory number 779, will be moved to a new location in the largest art museum in the world. The object is a small portrait of an obscure Florentine gentlewoman, painted on a thin panel of poplar. It is known to most of humanity - but not to France or Italy - as the Mona Lisa.

On Monday, for the first time in 31 years, other than Tuesday closings and occasional strikes, the best known, the most visited, the most written about, the most sung about, the most parodied work of art in the world, will not be on public display at the Musée du Louvre in Paris. On Wednesday at 2pm, amid great fanfare, she will reappear in a new, permanent home, better suited to her ceaseless, jostling crowds of admirers.

Contrary to initial reports, the Mona Lisa will not acquire every girl's heart's desire - a room of her own. The small painting - 77cm by 55cm (2ft 6in by 1ft 10in) - will hang alone on an enormous false wall, or screen, in a gallery full of other Italian paintings.

Leonardo da Vinci's masterpiece (one of the few paintings he finished) will be placed, once again, behind glass to protect her maddening smile from thieves, bullets, explosives, knives, spray cans and ballpoint pens. She will, however, no longer lurk in a gloomy hallway. She will stare her slightly cross-eyed, gently supercilious grin from just behind the armoured glass of a purpose-built "safe" sunk into the wall. Her pleasant features, her folded hands and the weird, blasted landscape behind her will be bathed in natural and artificial light in a room remodelled with a €4.8m (£3.3m) donation from the Japanese television network, NTV.

After 500 years, the Mona Lisa is in desperate need of cleaning. If she were any other painting, the Louvre would probably have taken the opportunity to remove the patina of half a millennium, and the darkening of an early misguided restoration, before displaying her in her new home.

With the Mona Lisa, cleaning is out of the question. She must remain precisely like the image of her implanted in the world's eye by countless reproductions, spoofs, pastiches and advertisements. And from Wednesday, Mona Lisa's admirers - an average of 1,500 people an hour - will be able to take a close look at her, grime and all, for the first time since she was placed behind glass 31 years ago.

There are 6,000 paintings in the Louvre. Ninety per cent of the museum's visitors make a beeline to the Mona Lisa. Most seem to spend no more than three minutes gazing at her. Many have their photo taken (breaking a rule which is rarely enforced). Then they leave. Some appear to go away disappointed. The most frequent comment is: "Isn't she small?" Mona Lisa has become a box to be ticked on the Paris tourist itinerary, alongside the Eiffel Tower and Notre Dame cathedral. She is a painting-superstar, a celeb, an icon, a spelling mistake.

Her name should really be Monna Lisa, abbreviation of Madonna Lisa or "my lady Lisa". The French call her " La Joconde", a pun on "amused woman" and the married name of Leonardo's presumed sitter, Lisa del Giocondo, née Gherardini.

Many theories have been advanced about who she "really" was, ranging from aristocrats and harlots to Leonardo da Vinci's mother and even a self-portrait of Leonardo in drag. (Further scientific "proof" of the cross-dressing self-portrait theory has recently been offered by American computer studies. The idea is not taken seriously by art historians.)

Why has this, of all paintings, become so famous? The Louvre is stuffed with wonderful paintings. Why do so many people throng to see this small, dark portrait of a grinning woman with no eyebrows? Is the Mona Lisa truly a transcendentally magnificent work of art? Or is she just famous because she is famous?

In a marvellous book, published in 2001, the British historian, Donald Sassoon, traced the origins of the Mona Lisa mystique through five centuries ( Mona Lisa: The History of the World's Most Famous Painting, Harper Collins paperback, £8.99). He concluded that there was something special about the painting itself. The pose and technique were regarded as revolutionary by contemporaries of Leonardo, including Michelangelo.

The brushstrokes are so fine - piled layer upon layer in a method called sfumato (smoky) pioneered by Leonardo - that they cannot be individually identified even under a microscope. The Lady Lisa's pose, turning slightly towards and looking at the viewer with no intervening barrier, was unorthodox in the early 1500s - and much copied. All the same, the beauty of the painting alone cannot explain Mona Lisa's fame, says Professor Sassoon.

Her status as "the one painting everyone knows" is, he says, the "product of a long history of political and geographical accident, fantasies conjured up, connections made, images manufactured, and luck." The painting appears to have been started in 1503. For reasons unknown, Leonardo did not hand the work over to Lisa Gherardini's husband, as originally commissioned. He took it with him when he was invited to the court of the French king, François I in 1516. In other words, Leonardo ran away with another man's wife - or at least her image. After the artist's death in France in 1519, the painting was bought by the king, entered the royal collection and then the state collection after the Revolution in 1789. She was displayed in the Empress Josephine's bedroom during Napoleon's reign and then placed in the Louvre.

Ending up in Paris - the most visited city in the world - was her first piece of "luck", although not at first. For half a century, she hung in the Louvre almost unnoticed. In the mid 19th century, she was rediscovered by British and French writers and turned into an object of mystery and almost an object of lust.

In 1869, the British art critic Walter Pater, in aninfluential passage later made into poetry by W B Yeats, promoted the Mona Lisa as a kind of elemental mother-temptress, madonna-femme fatale, uniting the age old male fantasies and myths of womanhood. "She is older than the rocks among which she sits; like the vampire she has been dead many times, and learned the secrets of the grave; and has been a diver in deep seas, and keeps their fallen day about her; and trafficked for strange webs with Eastern merchants; and, as Leda, was the mother of Helen of Troy, and, as Saint Anne, the mother of Mary..."

It was 19th-century art critics and writers who first became obsessed with Mona Lisa's smile. Too many theories about her curious expression have been put forward to list them all. Was she pregnant and therefore serene? Was she trying to smile without betraying the gaps in her teeth, which were common in the dentally challenged early 16th century? Whatever the explanation, there is something tantalisingly impermanent about the Mona Lisa's smile. Now you see it and now you don't. The smile, ignored for 350 years, is a large part of La Joconde's modern mystery and success.

So is her lack of eyebrows. Shaved brows may have been a 16th-century Florentine fashion. Alternatively they may have been removed by a clumsy restoration. Mistake, or not, the absence of eyebrows helps to give Mona Lisa her enigmatic expression. Draw on some eyebrows (on a photograph) and she becomes rather forbidding. Another piece of luck, maybe.

She was not a worldwide celebrity, however, until she was stolen from the Louvre by an Italian in 1911. The event provoked a xenophobic crisis in France, like a mini-Dreyfus affair. It was assumed at first that "foreign" and "avant -garde" artists were involved because they disapproved of bourgeois-approved, European high culture. Pablo Picasso, recently arrived from Spain, was interrogated. The Italian-born poet Guillaume Apollinaire was briefly imprisoned. By the time that she was recovered in Milan in 1913, Mona Lisa was a star.

In the 1960s and 1970s, she became a diplomat. She was loaned to the US by President Charles de Gaulle in an attempt to improve Franco-American relations. In 1974, she travelled to Japan and the Soviet Union. There was briefly a plan to loan her to London to celebrate Britain's entry to the EEC in 1973. Nothing came of it. Could Euro-scepticism have been cured for ever by Mona Lisa's smile? In the late 20th century, she became a canvas upon which contemporary artists, admen and comedians doodled. Already in 1919, the surrealist artist Marcel Duchamp had protested against the museumification of art - and made a name for himself - by producing a version of the Mona Lisa with a moustache and a goatee beard. He called his work LHOOQ, an early form of text message which reads aloud in French as " elle a chaud au cul" (she has a hot bum).

This was followed by Andy Warhol's multiple Mona Lisas, like strips of passport photos, Thirty are Better than One (1963); a Mona Lisa dressed as Mao, Mona Tse Tung by Roman Cieslewicz (1976); naked Mona Lisas; pregnant Mona Lisas; a Mona Lisa made out of toast; Mona Lisas as Jackie Kennedy or Monica Lewinsky; Monty Python's animated Mona Lisa and a disturbingly convincing drawing by the British cartoonist Steve Best in 1992. The cartoon's caption was: "Mona was trying not to smile as she waited for her silent fart to reach Leonardo."

The image of the Mona Lisa has also been hijacked to advertise everything from condoms to horsehair corsets, from oranges to inter-uterine devices. There have been references to her in pop songs from Cole Porter: "You're the Nile, You're the Tower of Pisa; You're the smile on the Mona Lisa"; from Nat King Cole: "Are you warm, are you real, Mona Lisa? Or just a cold and lonely, lovely work of art?"; and several appearances in the oeuvre of Elton John.

Such over-exposure has inevitably cheapened the Mona Lisa as a work of art. It has become difficult to look at the painting and separate it from the layers of pastiche and mockery and exploitation. On the other hand, the more Mona Lisa is exploited, mocked or ripped off, the greater her mystique and popularity becomes.

Professor Sassoon believes that this is a positive thing: a refreshing proof that popular culture and high culture can overlap. "It demonstrates that something can be both a classic of Western art and pop, hip and cool."

The Louvre, reading between the brushstrokes, is not so sure. The Mona Lisa is a terrific money-spinner. The Louvre gift shop sells more than 330,000 pieces of Jocondarama each year. But there is, one detects, something of an unease in the museum about sheltering a kitsch tourist attraction which is also a great work of art.

Officially, the Louvre now says that it never intended to give the Mona Lisa a room of her own. Museum officials say that they spoke four years ago of giving La Joconde a "space" of her own. Many interpreted that as meaning a "room". In fact what was meant, the museum says, was a wall. Hmmm.

There have been reports of a struggle of principle within the Louvre on what to do with NTV's donation. Some officials thought that the only way to manage the crowds was to put the Mona Lisa into solitary confinement.

Others thought that this would betray the museum's wider purpose - to educate the public on great art. They insisted that the Mona Lisa should be shown in context. The educators appear to have won the day over the tour operators.

When the Salle des Etats reopens to the public on Wednesday, the tiny Mona Lisa will face the gigantic painting of the Wedding at Cana by Veronesi (Venice, 16th century). In the same room, there will be 50 other 16th- century Venetian paintings, including Titians and Tintorettos. Far from having a room of her own, Mona Lisa will be in a dormitory of great, Italian art. The Louvre presumably hopes to persuade more of its visitors to look beyond the Mona Lisa and enjoy the rest of the riches that the museum has to offer.

Many visitors already do. But not all. On a brief observation this week, at least one in two of the celebrants of the Mona Lisa cult turned on their heel and walked straight out to the tour buses.