A few years ago the underrated Marmottan tacked "Monet" onto its official name—and justly so, as this is the largest collection of the artist's works anywhere. More than 100 pieces, donated by his son Michel, occupy a specially built basement gallery in an elegant 19th-century mansion, which was once the hunting lodge of the Duke de Valmy. Among them you can find such works as the Cathédrale de Rouen series (1892–96) and Impression: Soleil Levant (Impression: Sunrise, 1872), the painting that helped give the Impressionist movement its name. Other exhibits include letters exchanged by Impressionist painters Berthe Morisot and Mary Cassatt. Upstairs, the mansion still feels like a graciously decorated private home. Empire furnishings fill the salons overlooking the Jardin de Ranelagh on one side and the private yard on the other. There's also a captivating room of illuminated medieval manuscripts. To best understand the collection's context, buy an English-language catalog in the museum shop on your way in.