To mark the 60th birthday of Circulation Research (1953-2013), the editors have commissioned Circulation Research Classics, a series of commentaries highlighting seminal articles published in the journal over the past six decades that have importantly shaped cardiovascular research. Written by leading experts, Circulation Research Classics are intended to describe the impact of these articles on the field by putting them in a historical perspective. The concept of “classic” is inextricably linked to time—a classic is something that maintains its value regardless of its age. Thus, an important consideration in selecting the articles to be highlighted is that they have stood the test of time, which is the most reliable indicator of the value of scientific work. By looking back at the illustrious past of Circulation Research, we hope to promote a deeper appreciation of the contributions of this journal to the advancement of knowledge.