This review by Wagenseil and Mecham explores the structural and mechanical properties of the vascular extracellular matrix (ECM) in vertebrates, focusing on the aortic wall. The authors highlight how the composition and organization of the ECM, particularly the elastic fiber network, have evolved to enable large arteries to store and release energy during the cardiac cycle. They discuss the role of smooth muscle cells in producing a complex ECM that defines the mechanical properties of the adult vascular system. The review also examines the evolutionary changes in ECM components as the cardiovascular system became more advanced, and how these changes affect vessel mechanics. Additionally, the authors correlate vessel mechanics with physiological blood pressure across different species and in mice with altered vessel compliance, suggesting a universal elastic modulus that controls ECM deposition. The review further discusses mechanical models for designing better tissue-engineered vessels and testing clinical treatments. The introduction provides background on the importance of elastic vessels in the closed circulatory system and the transition from invertebrate to vertebrate circulatory systems. The following sections detail the structure of the arterial wall, including the intima, media, and adventitia, and the development of the cardiovascular system. The role of vascular smooth muscle cells (SMCs) in ECM production and differentiation is also discussed, along with the expression profiles of key ECM proteins such as elastin, fibrillins, microfibril-associated glycoproteins, fibulins, EMILIN-1, lysyl oxidase, and collagens. The review concludes with insights into the functional significance of these proteins and their roles in maintaining vascular health and function.This review by Wagenseil and Mecham explores the structural and mechanical properties of the vascular extracellular matrix (ECM) in vertebrates, focusing on the aortic wall. The authors highlight how the composition and organization of the ECM, particularly the elastic fiber network, have evolved to enable large arteries to store and release energy during the cardiac cycle. They discuss the role of smooth muscle cells in producing a complex ECM that defines the mechanical properties of the adult vascular system. The review also examines the evolutionary changes in ECM components as the cardiovascular system became more advanced, and how these changes affect vessel mechanics. Additionally, the authors correlate vessel mechanics with physiological blood pressure across different species and in mice with altered vessel compliance, suggesting a universal elastic modulus that controls ECM deposition. The review further discusses mechanical models for designing better tissue-engineered vessels and testing clinical treatments. The introduction provides background on the importance of elastic vessels in the closed circulatory system and the transition from invertebrate to vertebrate circulatory systems. The following sections detail the structure of the arterial wall, including the intima, media, and adventitia, and the development of the cardiovascular system. The role of vascular smooth muscle cells (SMCs) in ECM production and differentiation is also discussed, along with the expression profiles of key ECM proteins such as elastin, fibrillins, microfibril-associated glycoproteins, fibulins, EMILIN-1, lysyl oxidase, and collagens. The review concludes with insights into the functional significance of these proteins and their roles in maintaining vascular health and function.