With all due respect to Les Paul, few names loom larger in American luthier lore than Christian Frederick Martin. The German immigrant crossed the Atlantic in the 1830s and began fashioning six-strings in the Spanish style (figure-eights with super pretty rosewood inlays), but with sturdier and more streamlined construction. He also experimented with new design flourishes, some of which were later adapted by makers like Fender. This exhibit boasts 22 of his original creations, plus more than a dozen 19th-century guitars from overseas crafters. A major gem from the company Martin founded—the acoustic used by Eric Clapton in his 1992 MTV Unplugged performance—is also on view. Through Dec 7.