A storage facility on Manhattan’s Upper East Side seems like an unlikely spot for a religious moment. Yet as Osei Essed cradled a 79-year-old Euphonon guitar with two hands and lifted it toward his head, the musician and salesman at the Brooklyn vintage-stringed-instrument store/temple Retrofret resembled nothing so much as a priest raising a chalice to his lips.

Essed lowered his nose to the guitar’s sound hole and inhaled. The purpose was practical rather than spiritual: If the Euphonon had been repaired recently, he explained, the glue would give off a telltale odor. As Essed put it, an old guitar should have a scent “like grandmother’s attic” if it hasn’t been worked on in the recent past. That observation caused his boss, Retrofret owner Steve Uhrik, to muse on the glues used in antique guitars, which he says were rendered from horses or rabbits.

Call it the intersection of the sacred — and the earthy. Inside that Manhattan warehouse is the vast majority of a collection of 265 rare guitars that will go on auction on April 2 and 3 in New York. Dubbed “The Artistry of the Guitar,” it includes showstoppers such as a 1930 Martin OM-45 Deluxe — one of only 14 ever made — an 1862 Antonio de Torres classical model, and coveted archtops made by the legendary John D’Angelico. Other makers range from Arcangel to Epiphone to Prairie State to Stromberg to Washburn to Weissenborn. A handful have a celebrity provenance — a 1941 Gibson SJ-200 once owned by Stephen Stills stands out — but in large part the instruments themselves will be the stars of this show.

The sale is being conducted by Guernsey’s, which has experience in what musicians might consider holy relics. In 2005, for example, it auctioned John Coltrane’s tenor saxophone, Charlie Parker’s alto, one of Dizzy Gillespie’s famously angled trumpets, and a clarinet of Benny Goodman’s. Before that, Guernsey’s also offered two custom-made electric guitars (the “Tiger” and the “Wolf”) built for the late Jerry Garcia. Arlan Ettinger, who co-founded Guernsey’s with his wife Barbara Mintz, describes “Wall Street types coming to the previews of the Garcia show and getting down on all fours to look” at Tiger and Wolf through the glass showcase windows. Some, he says, asked to touch the instruments and, when granted permission, kissed them reverently. (Ettinger and Mintz both come from the advertising world, and Ettinger contends that Guernsey’s stands out among much larger rivals for its marketing pizzazz and its ability to infuse a sense of story into a collection. Other marquee auctions handled by their firm have included documents, artifacts, and memorabilia relating to John F. Kennedy, Elvis Presley, Mickey Mantle, as well as Mark McGwire’s 70th home run ball.)

Fortune was offered a sneak peek at Guernsey’s stunning guitar collection, and since our enthusiasm for the instruments far exceeds our knowledge and acumen, we invited Essed and Uhrik to join us as expert guides. Click through the gallery to see and read about some of their favorites, along with several other notables.