Building 20 was an apartment house on the NIH campus for nurses, heart surgeons, foreign scientists, NIH directors, etc. Construction began in 1952 and occupancy was in 1954. The building was known for its cosmopolitan community and was the home of many NIH staff for decades--they raised their families there and eventually retired from there. During some of its lifetime, the building also served as a guest house for patients. The building was torn down for construction of the Clinical Research Center in 1998.