Each day, around 30,000 people visit the Louvre—the world's largest museum and a historic landmark in Paris—to view priceless artworks like Leonardo da Vinci’s Mona Lisa and the Venus de Milo. Today, that number will drop to zero, CNN reports. Heavy rains have caused the Seine River to flood, and both the storied museum and its neighbor, the Musée d'Orsay, shut down early last night so staff members could move the treasures to higher ground. Both institutions will remain closed today, and the Musee d'Orsay won’t re-open until Tuesday.

The Louvre’s underground floors are equipped with anti-flood pumps and sealed waterproof doors, but the museum doesn’t want to take any chances. According to The Independent, tens of thousands of “reserve” paintings and sculptures in storage will be evacuated from the Louvre and taken to the museum’s upper floors. (The Louvre has around 460,000 works of art, but only 35,000 are on public display.) Meanwhile, the AFP writes that the Musee d’Orsay has already moved much of its reserve collection off-site, and is running an emergency generator on its roof in case power cuts out.

Staffers will have to act fast: The Louvre’s emergency plan for flooding calls for the artworks to be removed from its underground reserve in 72 hours. The Musee d'Orsay has 96 hours. Thankfully, both museums prepared for the occasion during flood drills held earlier this year.

Over the past few days, copious amounts of rainfall have caused raging floods in central and northeastern France, prompting thousands of people to evacuate. By Friday afternoon, the Seine had risen about 18.5 feet above its typical level, The New York Times reports. It’s expected to reach 21 feet tonight. (Record flood levels were recorded in 1910, when the waterline reached 28 feet in central Paris.)

[h/t CNN]