In 1899, at the invitation of G. Stanley Hall, the great psychologist and President of Clark University, Santiago Ramón y Cajal, and four other European scientists of significant note, were invited to participate in the Decennial Celebration of Clark. Cajal, accompanied by his wife, arrived in Worcester, via New York, to much acclaim and praise in the local press. His three lectures, all delivered in French and illustrated with large color drawings made upon his arrival at Clark, were concerned with previously unpublished observations on the structure of the human cerebral cortex. The full text of these lectures and 31 illustrations (in black and white) were published, in English, in a large Decennial Volume prepared by Clark University. At the culmination of the Clark Celebration, Cajal, and the other invited attendees, received the honorary Doctor of Laws degree. Cajal, ever the scholar, visited many sites of interest in the Northeastern US prior to his return to Spain including Columbia, Harvard, and the University of New York. This paper details the events surrounding Cajal's visit to Clark University, his only visit to the United States.