Musée de l'Orangerie is located in the Tuilerie Garden, on the other side of the Seine river, in front of Orsay museum; The closest Métro stop is Concorde (Line 1, 8, 12). It is closed on Tuesdays. 

 This little museum is absolutly beautiful, you will find Monet's Nymphéas, in a room imagined as Monet imagined it himself!

There are also many paintings from the Late 19th and the beginning of the 20th century, like Picasso's paintings, Modigliani's but also Parisian painters like Maurice Utrillo (the only impressionist paintors borned in Montmartre!), Renoir or le Douanier Rousseau. 

 It is a little museum, less crowded than the Louvre or Orsay but that definitly worth taking a tour inside!

When you go out of the museum, and look for Concorde square, you also have a wonderful panoramic view, with the French Parlement (l'Assemblée Nationale), the Eiffel tower, the Grand Palais, the square with the beautiful Hotel Crillon, the Obelix, the beginning of the Champs-Elysées, and if it is winter, the Arc de Triomphe (otherwise it is hidden by the leath of tree).