The Piano Lesson, 1916 The Museum of Modern Art hide caption

itoggle caption The Museum of Modern Art

Nancy Astor, pictured here in a John Singer Sargent portrait from 1909, represents the 19th-century American feminine ideal: soft, delicate, and clad in European-made clothes. As the 20th century developed, that ideal shifted. National Trust / Art Resource hide caption

itoggle caption National Trust / Art Resource

One of the negatives discovered by Rick Norsigian. Courtesy Rick Norsigian hide caption

itoggle caption Courtesy Rick Norsigian

The restored version of "The Gross Clinic," above, is characterized by darker hues that bring the image closer to what Thomas Eakins originally painted in 1875. The Philadelphia Museum of Art hide caption

itoggle caption The Philadelphia Museum of Art

A self-portrait by Rembrandt, valued at $36 million, was taken from the Swedish National Museum in 2000. Robert Wittman, founder of the FBI's Art Crime Team, went undercover — as an authenticator for an Eastern European mob group — to recover it. Swedish National Museum hide caption

itoggle caption Swedish National Museum

Claude Monet bought his house in Giverny seven years after he first started renting it. He worked hard to create the gardens, later featured in his paintings, around his home. Fondation Claude Monet hide caption

itoggle caption Fondation Claude Monet
Claude Monet