Though Maison Bonnet is still relatively little-known, almost everyone has seen the house’s glasses: After all, this fourth-generation, Maitre d’Art-recognized, family-run business, which was officially established in 1950, has made some of the most iconic frames around. Yves Saint Laurent, Le Corbusier, Jackie Onassis, and Jacques Chirac were all clients. While you won’t be able to pick up a pair at your local optometrist’s office, you can visit their appointment-only Paris outpost, which actually just opened in 2009 (the company operates out of a workshop in Sens, Burgundy). There, a master craftsman will map your entire face, measuring three different angles of your nose, the gap between your temples, the overall structure of your skull, the shape and tenor of your cheekbones and eyes, etc. One pair of glasses requires three visits (the final two can be condensed, for those who are visiting), and while they’re revered for their work in tortoise shell, they do more affordable versions in horn and acetate as well.