The Orsay contains the Louvre's collection of art from 1848 through 1914, creating a bridge between the Louvre's displays and the modern art collections shown in the Pompidou and the Musée Moderne. And a fabulous collection it is, with paintings from Delacroix to van Gogh and decorative objects from Second Empire eclecticism to Hector Guimard's Art Nouveau mastery. Part of the building has been under renovation since the turn of the millennium; by early 2005 the scaffolding should be cleared away.

By 1939 the Gare d'Orsay had become too small for anything except suburban trains. Closed in the '60s, the dusty station was used as a theater, an auction house, and a setting for Orson Welles's movie The Trial before it was finally slated for demolition. However, the destruction of the 19th-century Les Halles (market halls) across the Seine provoked a furor among conservationists, and in the late 1970s former president Giscard d'Estaing ordered that the Orsay be transformed into a museum. Architects Pierre Colboc, Renaud Bardou, and Jean-Paul Philippon were commissioned to remodel the building; Gae Aulenti, known for her renovation of the Palazzo Grassi in Venice, was hired to reshape the interior. Aulenti's modern design provoked much controversy, but the museum's attributes soon outweighed any criticism when it opened in December 1986.

The museum is arranged on three floors. Paintings are hung in wings accessible from this main gallery. Don't miss the large Salle 7, which contains Courbet's difficult masterpieces L'Enterrement à Ornans and L'Atelier du Peintre. Courbet's realist painting influenced the Impressionists, whose work is upstairs. Also on the ground floor are little-known academic painters who demonstrate the prevailing artistic atmosphere of the period.

There are also more experimental visions, from Gustave Moreau's myth-laden decadence to Puvis de Chavanne's surprisingly modern line. This makes the leap into Impressionism much easier to understand; by Salle 14 the radical movement has been launched with Edouard Manet's revolutionary reworking of a classical motif in his reclining nude Olympia. When it was first shown, in 1865, Olympia's frank, cooly direct gaze was more than Parisian proprieties could stand; her unfinished hands were derided as monkey paws and the black cat (a symbol of female sexuality) was considered outrageous. Across from Olympia's I-dare-you-to-look smile, you'll find two pieces from Claude Monet's great unfinished Déjeuner sur l'Herbe, painted in response to his friend Manet's painting of the same name (now upstairs).

The great hall also contains two separate temporary exhibition spaces -- painting to the left, photography to the right. And at the rear of the great hall is a wonderful display about the Opéra neighborhood, complete with a to-scale model under the glass floor. From here take the long escalators to the top floor, where Impressionism really gets going. Up here you'll find Manet's Déjeuner sur l'Herbe (Lunch on the Grass), the painting that scandalized Paris in 1863 at the Salon des Refusés, an exhibit organized by artists refused permission to show their work at the academy's official annual salon.

This top-floor collection allows Impressionism to break free of its clichés: here Monet's Les Coquelicots (Poppy Fields) appears perfectly fresh in the sparkling company of small works by Alfred Sisley, Pissarro, and Degas. Daring curator choices also allow for interesting juxtapositions and thoughtful comparisons, such as the positioning of Gustave Caillebotte's floor scrapers, or James Whistler's portrait of his mother, alongside Impressionist contemporaries. It's also a pleasure to see work by one of the few successful female Impressionists, Berthe Morisot, displayed among her contemporaries.

In Salle 36 modernism begins breaking into the Impressionist idyll. Cézanne's darker palette, blocky brushstrokes, and shifting perspectives set the stage for a postwar revolution. The Postimpressionist galleries include world-famous works by van Gogh, Paul Gauguin, and Toulouse-Lautrec, along with the delicate pastels of Odilon Redon. The collection then moves downstairs to the middle floor, via some small galleries of the Kaganovitch collection.

The middle floor offers two serious treats: a charming restaurant and an exquisite collection of Art Nouveau furniture and decorative objects. Here you can see rare surviving works by Hector Guimard (designer of the swooping green Paris métro entrances) and Barcelona maestro Antoni Gaudí, along with glassware by Lalique and Tiffany, furniture by Carlo Bugatti, and arts and crafts masterpieces. Keep an eye out for the useful explanatory boards available at the entrance to Salle 65, among other locations; these English-language texts give helpful pointers about what you're looking at. COST: EUR7, Sun. EUR5. Métro: Solférino; RER: Musée d'Orsay.