In making the invisible universe visible, radio telescopes allow astronomers to see through our local universe of nearby stars to view a distant universe. Radio astronomy has provided tremendous insights into the composition, physical characteristics, and evolution of objects in the universe and revealed completely new, unanticipated phenomena. The National Radio Astronomy Observatory (NRAO) has greatly contributed to this scientific revolution. The book traces the story of radio astronomy from its accidental beginnings in the 1930s to the present, describes the development of NRAO instrumentation, and focuses on the considerable contributions made by the scientists using the NRAO instruments. This unique insight into the evolution of a truly modern science is written in a style that anyone with an interest in astronomy can understand and enjoy, and also provides technical information that professionals in astronomy, computer science, and electrical engineering will find useful.