The Rest was constructed in 1882 and served as Saint Elizabeths mortuary and pathology lab. One of the most prominent figures to work in The Rest was Dr. Isaac Wright Blackburn. Blackburn was appointed special pathologist at the hospital in 1884, and was a leading pioneer in the study of mental illness.
During his time at Saint Elizabeths, Blackburn published one of his most famous works, Gross Morbid Anatomy of the Brain, as well as detailed drawings and photographs of the brain. By 1900, he had established a collection of more than 1,000 brain specimens that helped establish a universal set of reference data for teaching and scientific purposes. Some of these tissue samples are on display in the new Saint Elizabeths Hospital complex today.
In addition to Blackburn’s work, during the 1930s, Saint Elizabeths became an important resource for films that documented live patients and their brains after they passed away. All of these resources were shared across the country for other professionals in the field. This work made Saint Elizabeths a leading figure in the medical field. In 1924, a new lab was constructed on the hospital's East Campus and named the Blackburn Laboratory in his honor.
The building includes two stories and a basement. During its time as a lab and mortuary, it included special arrangements and features to help care for, and preserve, the remains of patients who passed away until their families could make arrangements. The floor plan is open and includes many windows that allow natural light, which benefited the Circulating Library that would later move in. Offices for staff were found on the second floor.
By 1929, the mortuary and pathology lab had been moved out of The Rest, and the Circulating Library had been moved in to take its place.