Here's a question for your next trivia quiz: What color is the Eiffel Tower?
Actually, it's a trick question. The Eiffel Tower is painted three different colors, or at least three different shades of a specially mixed "Eiffel Tower Brown" exclusive to Paris's icon.
"Not many people know that," says Jean Louis Rabaté. "But by painting the bottom of the tower a darker color, and the top paler, it gives the visitor a more aesthetic impression," accentuating the structure's elegance.
Mr. Rabaté knows everything there is to know about painting the Eiffel Tower.
Like his father before him, he is the monument's chief paint expert. And he is coming into his own at the moment, as he prepares for the tower's eighteenth paint job, set to commence on December 3.
It's not just a matter of color, although the appropriate hue for Paris' best-loved symbol has long been a matter of debate: Even the Academie Française, the 100-strong elite group that guards the purity of the French language and culture, has weighed in (favoring grey-blue, unsuccessfully).
Gustave Eiffel painted his creation red when he constructed it in 1889. The tower, erected that year for the International Exposition and for the centennial celebration of the French Revolution, has turned yellow, beige and brick over the years.
Since 1968, however, the 984-foot-high structure has been 'Eiffel Tower Brown,' judged the color that best brings out its silhouette against an all-too-often cloudy sky.
One of the perks of being mayor of Paris is being able to pick the Eiffel Tower's color, but current Mayor Bertrand Delanoë has chosen not to go splashy.
Instead, as he launched what is known formally as "The 18th Painting Campaign," he imbued the task with nobility and gravitas.
"The beauty and prestige of one of the best known monuments in the world depends on their work," he said of the 25 men who will do the job.
And, he might have added, the stability - for it is only the paint that keeps the iron structure, made up of 18,000 girders riveted together, from rusting and collapsing.
As Mr. Eiffel himself said, "one cannot emphasize enough that painting is the essential means of conserving a metallic structure, and the care devoted to it is the only guarantee of its durability."
So, over the next 15 months, 25 men, equipped like mountain climbers, and secured by 50 kilometers of lifelines will be crawling all over the Eiffel Tower, using round-headed paintbrushes in every nook and cranny. They expect to get through 1,500 of the brushes.
No paint guns are allowed. "We don't want to paint the whole neighborhood this color," says chief engineer Yannick Bourse.
By the time they have finished, they will have applied 60 tons of paint, and therein lies a problem - because neither Mr. Bourse nor any of his predecessors has found a way of stripping off previous coats of paint without closing the tower to visitors, which is unthinkable.
In the seven years between paint jobs, about 20 tons evaporates or erodes, but that still leaves 40 tons more weight on the tower each time. After 17 paint jobs, it is about 700 tons heavier than Eiffel designed it to be.
This does not pose any immediate danger, Bourse is quick to reassure visitors: The weight is evenly distributed, and the tower can withstand an extra 700 tons without any difficulty.
But one day a solution is going to have to be found, because, as Bourse says lovingly, "The Eiffel Tower is eternal."