We carry out a brief review of Santiago Ramón y Cajal's life. Cajal was born on 1 May 1852 in Petilla de Aragón (Spain) and died on 17 October 1934 in Madrid. He graduated in medicine at the University of Saragossa in 1873 and successively occupied the chair of Anatomy in Valencia (1884-1887), and Histology and Pathology in Barcelona (1888-1891) and Madrid (1892-1922). Starting from the modified Golgi staining method applied to embrions or young animals, Cajal published a monumental histology of the nervous system creating the revolutionary concept of the neuron doctrine and dynamic polarization of the neuron. He also introduced new staining methods including reduced silver nitrate, formol-urano and sublimate gold. He then procceded to study the process of degeneration and regeneration of the nervous system and the fine texture of the neuron and neuroglia. Together with Golgi, Cajal was awarded the Nobel prize for Physiology and Medicine in 1906. Don Santiago was also an excellent teacher, painter, photographer and writer. He is the greatest of all Spanish scientists, the most cited classical scientist and the chief architect of the neuron theory.