Original unit in complex forming one of the great observatory centers of the world. Built in the 1930s under terms of legacy from William Johnson McDonald (1844-1926), a Paris (Texas) banker interested in the stars. A well-educated man, McDonald lived frugally. As a hobby, he read science books and viewed planets through a small telescope. His will granted to the University of Texas $800,000: "to build an observatory and promote the study of astronomy." This site was selected because of its high ratio of clear nights, its 6,800-foot altitude, and its quite low latitude that permits observation of southern skies. The observatory was operated for its first 25 years mainly by astronomers from the University of Chicago, more recently primarily from the University of Texas. Until 1948, its 82-inch telescope was second largest in the world. Its fine work and site have resulted in the addition of other telescopes including a 107-inch instrument sponsored jointly by the National Aeronautics and Space Administration, the National Science Foundation, and the University of Texas. Discoveries made here have included interstellar polarization and the satellites of several planets.