Continuing the series on medical history, this article explores key 20th-century breakthroughs, including the 1953 discovery of the DNA double helix by Francis Crick and James Watson in Cambridge, the development of polio vaccines by Jonas Salk and Albert Sabin, and the 1960 introduction of the contraceptive pill, supported by Katharine McCormick. These milestones significantly advanced disease prevention, public health, and reproductive autonomy.