, Jan. 14 -- Queues stretching beneath I.M. Pei's iconic glass pyramid have long been a defining part of a visit to the Louvre, rivaling even the draw of the Mona Lisa.

Now, the world's most visited museum is raising the cost of entry for many travelers as it seeks funds to address mounting challenges-from overcrowding and security needs to labor unrest and the fallout from October's high-profile theft of the French Crown Jewels. The museum was forced to close again on Monday following a staff walkout.

Beginning Wednesday, the Paris landmark will implement a two-tier pricing system, increasing ticket prices for most non-European visitors to 32 euros ($37), up from 22 euros ($26). The overnight rise amounts to a 45% increase.

The new ra...