PARIS — For six generations, in the foothills of the Italian Alps, the Loro Piana family has been spinning wool from cashmere goats, Merino sheep and Andean vicuña into some of the most expensive yarn in the world.

Now, for the first time, the company’s Roccapietra mill will open its doors to the public. It will happen on May 20-22, part of Les Journées Particulières, a three-day event in which the French luxury giant LVMH Moët Hennessy Louis Vuitton lifts the curtain on some of the studios and workshops of its 70 brands.

In 2011 and 2013, more than 100,000 visitors watched shoemakers add the final flourishes to custom Berluti shoes, horologists piece together TAG Heuer watches and petites mains embroider beads onto the bodices of Dior gowns. (The event is held irregularly.)

The idea is a play on the Journées du Patrimoine, or Heritage Days, held in France, when official buildings like the Palais de Congrès and the Élysée Palace are opened to the public.

Antoine Arnault, chief executive of Berluti, chairman of Loro Piana and the son of the LVMH founder, Bernard Arnault, said he initiated the event to show that LVMH is more than just a stock listing.

“The group is not built by finance,” he said. “The group is made of tens of thousands of people who are proud of what they do, who love what they do, who work in fantastic conditions.”

Mr. Arnault said he knows visitors are excited to visit the ateliers, but the event really is for the artisans: “They’re there all year long making these beautiful products a little bit in the shadows, and you feel their pride.”

This year, 51 locations across Europe are opening, several of them for the first time. In addition to Loro Piana’s mill, they include Fendi’s headquarters and fur workshop at the Palazzo Della Civiltà Italiana in Rome, where a visit is as much about the architecture as the artisans. Commissioned by Benito Mussolini in the 1930s, the Square Colosseum, as it is commonly called, is a towering block of travertine marble perforated on all sides by a grid of Roman archways.

This year Les Journées Particulaires will put special emphasis on the transmission of savoir-faire, and there will be a variety of master classes, like a barbering workshop with Acqua di Parma, and a session on the art of custom-made dress shirts with the British brand Thomas Pink.

In another first, teams from Instagram and Facebook will document this year’s visits in real time to expand the access.

Registration begins April 21 on the LVMH website. Potential visitors are being encouraged to create accounts in advance to speed the process once reservations open, because space is limited and tends to fill quickly.

As for the event itself, Mr. Arnault has a personal goal: “We hope to beat the record of Beyoncé. She sold out her last concert in 3 minutes. We think we can do better.”