Michael McBride's Freshman Organic Chemistry II lecture at Yale (CHEM 125B) traces how chemists determined glucose's structure before modern spectroscopy existed. McBride opens with IR, NMR, and X-ray views of glucose's pyranose ring, then walks back to 1887, when Heinrich Kiliani established glucose as an aldohexose and, with Emil Fischer, developed a method for homologating aldoses. He details Fischer's use of crystalline osazones and his Fischer projections to argue, in 1892, which of eight possible aldohexose configurations matches glucose, a proof that also validated van't Hoff's stereochemical theory. The lecture closes with a different synthesis problem: Cram, Tanner, and Thomas's 1991 preparation of antiaromatic cyclobutadiene inside a custom-built clamshell molecule, isolating a molecule too reactive to exist freely, and their NMR evidence for its antiaromaticity. Chapter markers separate the historical proof from the modern synthesis.