Elizabeth Dent, exhibition associate, National Gallery of Art. In 2014 the National Gallery of Art acquired a thirteenth-century French stained glass window from the Corcoran Gallery of Art. Originating in Soissons Cathedral in northern France, the window came into possession of Senator William A. Clark of Montana (1839–1925) around the turn of the century and was installed in the billiard room of his 121-room mansion on Fifth Avenue in New York City, popularly referred to as “Clark’s Folly.” In this lecture, as part of the Works in Progress Lecture Series, on April 15, 2019 Elizabeth Dent discusses the iconography and history of the window, from its original devotional contexts at Soissons to its acquisition by Clark and its role within the decorative scheme of the mansion.