Whitin Observatory, Wellesley College’s astronomical observatory in Massachusetts, was built in 1900 through the support of trustee Sarah Elizabeth Whitin and became the home of the college’s new astronomy department under Sarah Frances Whiting. Inspired by their 1896 discussion of a 12-inch refracting telescope, Whitin expanded an initial modest plan into a white-marble observatory that opened with equipment for observation, photometry, and spectroscopy. Enlarged by 1906 and later expanded again, it also served an unusual wartime role in 1942, when a secret cryptography course met there. The observatory has long supported women’s astronomy education, research, and teaching while continuing in active scientific use.