Yerkes Observatory is a renowned astronomical research facility located in Williams Bay, Wisconsin. Established in 1897 by George Ellery Hale, it is famous for housing the largest refracting telescope in the world, with a lens diameter of 40 inches. The observatory has played a significant role in the development of modern astronomy and has contributed to various discoveries. The observatory is part of the University of Chicago and has been a center for astronomical research and education for over a century. It offers public outreach programs, allowing visitors to learn about the universe and view celestial objects through its telescopes.