PARIS -- The self-styled fountain of world civilization has begun to overflow.

After days of heavy and historic rainfall across continental Europe, the Seine, which normally flows gracefully under the arches of 37 bridges in Paris, dramatically overflowed its banks.

Many of the most important sites in the French capital sit right off the river, including the National Assembly, the French Foreign Ministry, and the Eiffel Tower.

As of Thursday afternoon, Paris’s two most famous museums were not taking any chances with the priceless treasures they hold.

The Louvre Museum — the home of the Mona Lisa and the largest art gallery in the world — began evacuating certain pieces from its collections held underground. The museum stretches along the Seine for several city blocks.

Directly across the river, on the Left Bank, sits the Musée d’Orsay, a 19th-century train station that now holds the world’s most extensive collection of Impressionist and post-Impressionist art.

On Thursday, the Orsay closed early and said in a statement that a ‘‘crisis management team’’ had been organized to move some of its most important pieces if the river rises above 18 feet.

‘‘The museum has already transferred a good part of its reserves in outside storage buildings,’’ the statement said.

Washington Post