Paris is a city of museums, nearly 150 by my unofficial count. Beyond the state-owned grandes dames — the Louvre, the Musée d’Orsay and Versailles (if you define a palace as a museum) — there are free city museums (the Petit Palais and the Carnavalet, among them), and museums dedicated to one artist (Rodin, Picasso), one writer (Balzac, George Sand), one subject (perfume, playing cards), even one activity (counterfeiting, smoking).

But some of the most intriguing collections may be ones you’ve never heard of, sequestered in hidden spaces. Here are three museum spaces that even many Parisians have never heard of.

Consultation Room for Prints and Drawings at the Louvre

Tucked away at the far end of the sprawling Louvre is an intimate, little-visited wing: the Graphic Arts Department’s Consultation Room, whose entrance, guarded by two stone lions, faces the Carrousel Garden abutting the Tuileries Garden. There you can see works by some of the world’s most famous artists up close, out of their frames, for as long as you want.

The Louvre does not advertise how to visit the Consultation Room. The department houses almost a quarter of a million drawings, pastels, miniatures, prints, engraved plates, rare books, autographs, woodcuts, lithographic stones and manuscripts, most of which never see daylight.

It takes perseverance to visit. Through the Louvre’s website, you must submit a request in French for an appointment with the name and number of up to 10 portfolios from the museum’s online catalog. Then you wait for a written acceptance, typically sent within a few days.