Since 1927, this former royal greenhouse has been the home of Monet’s stunning Nymphéas, or water lilies, which he conceived as a “haven of peaceful meditation.” Two large oval rooms are dedicated to these masterpieces, in which Monet tried to replicate the feeling and atmosphere of his garden at Giverny. He worked on these enormous canvases for 12 years, with the idea of creating an environment that would soothe the “overworked nerves” of modern men and women—in what might be called one of the world’s first art installations.

The other highlight here is the Guillaume collection, an impressive assortment of late-19th- and early-20th-century paintings. It’s on the lower level, where the first, light-filled gallery displays mostly portraits and still lifes, such as Renoir’s glowing, idyllic Femme Nu dans un Paysage, and Cézanne’s rather dour-looking Madame Cézanne. The rest of the collection is under artificial lights: slightly sinister landscapes by Rousseau, enigmatic portraits by Modigliani, distorted figures by Soutine, as well as some kinder, gentler Picassos (Les Adolescents bathed in pink and rust tones). This collection has a stormy history—after Guillaume’s death, his rather flamboyant wife rearranged the collection to her own taste, selling off some of the more “difficult” paintings. The result is a lovely collection that lacks a certain bite; truly impressive works by these masters can be seen elsewhere.