PARIS — Long lines beneath I.M. Pei’s glass pyramid in Paris have become as much a part of the experience as the “Mona Lisa” itself.

Now the Louvre is putting a higher price on that pilgrimage, raising admission prices for most non-European visitors by nearly half as it tries to shore up finances after repeated strikes, chronic overcrowding — and a brazen French Crown Jewels heist that shook the institution.

The museum said the 45% price hike to $37 from $25.50 is part of a national “differentiated pricing” policy announced early last year that’s coming into force across major cultural sites, including the Versailles Palace, the Paris Opera and the Sainte-Chapelle.

But French worker unions have denounced the Louvre ticketing change, saying it undermines the universal mission of the world’s most visited museum — home to the “Venus de Milo” and the “Winged Victory of Samothrace.”

Some visitors echoed those concerns.

“Culture should be open to everyone — yes — at the same price,” said Laurent Vallet, visiting Paris from Burgundy.

The change affects visitors from most non-EU countries, including the United States, which typically accounts for the majority of the Louvre’s foreign tourists.

Under the new structure, visitors who are neither citizens nor residents of the EU — or Iceland, Liechtenstein and Norway — will pay the higher rate.

While some tourists questioned the logic of charging visitors more, others said they would pay anyway. “It’s one of the main attractions here in Paris … We’re still going to go,” said Allison Moore, a Canadian tourist from Newfoundland visiting with her mother. “Hopefully it’ll be all worth it in the end.”