'Private Treasures: Four Centuries of European Master Drawings' offers a selection of works from one of America's most significant private collections of master drawings. The exhibition, on view at the National Gallery of Art, Washington, from May 6 through September 16, features 100 of the finest drawings from the collection, and represents 85 artists of the Italian, French, Dutch, Flemish, German, Swiss, British, and Swedish schools from the 16th to the 20th centuries.