This book is devoted to the installation at the Chinati Foundation in Marfa, Texas, by the great light and space artist Robert Irwin. After seventeen years of preparation the artwork opened to the public in July 2016. Along with the building-developed by Irwin, with its directed lighting filling the space-the design of the courtyard forms an apex in the body of work by this pioneer of contemporary American art. At the same time, it fulfills the long-cherished wish of Donald Judd, the founder of the Chinati Foundation, to have a major work by Irwin in his artists’ museum. This monograph describes Irwin’s friendship with Judd and Judd’s interest in Irwin’s art, which led to an invitation to Marfa in 1999. It presents Irwin’s work in photographs documenting the light over the course of a year. Essays, drawings, floor plans, and other pictures show this work within the larger context of Irwin’s oeuvre and the Chinati Foundation’s collection.