Founded in 1892 and dedicated in 1897 in Williams Bay, Wisconsin, Yerkes Observatory became closely linked with the University of Chicago and helped define modern astrophysics by uniting telescope observation with laboratory physics and chemistry. Its 40-inch refracting telescope, still the largest refractor ever successfully used for astronomical observation, made it internationally renowned. For more than a century, the observatory supported major research in stellar classification, solar studies, nebulae, and other fields, while building a vast photographic archive. After closing as a university observatory in 2018, it passed to the Yerkes Future Foundation in 2020 and reopened in 2022 as a restored scientific landmark for public education.