Shoes, bags, and coats are all well and good, but my real addiction? Glasses. No matter what the weather is like or where I’m going, I always travel with at least two pairs of shades and my prescription glasses in my bag—I’ve even begun wearing transition sunglasses at night, as they adjust to any light and just make every outfit cooler. So, naturally, I was overjoyed when I got the opportunity to visit EssilorLuxottica’s factory and headquarters on the outskirts of Milan, Italy, earlier this year.

The Italian-based eyewear company is the largest in the world and commands more than one-quarter of global eyewear sales. It owns major retail stores, including LensCrafters, Sunglass Hut, Pearle Vision, Target Optical, and Glasses.com. It also owns and manufactures eyewear brands Ray-Ban, Oliver Peoples, Oakley, and Persol—its crown jewel—and licenses prescription and non-prescription glasses for dozens of luxury brands, including Chanel, Prada, Miu Miu, Tiffany & Co., and Ralph Lauren, to name just a few.

The history of sunglasses is long and wildly interesting. It actually all started with ancient tribes, who cut slits in animal bones to shield their eyes from the sun. Centuries later, in 1929, American entrepreneur Sam Foster started the mass production of commercial sunglasses. (His company, Foster Grant, is now owned by EssilorLuxottica.) The Army Air Corps soon commissioned glasses to help protect pilots’ sight, and with that, Ray-Ban’s iconic aviators were born. A few years later, in 1961, Luxottica (its name before it merged with French multinational corporation Essilor) was founded in the small but lively Italian town of Agordo by Leonardo Del Vecchio, as a sunglasses manufacturer. The first designer it signed was Giorgio Armani, ushering in a new era of glasses-as-accessories. And from there, the eyewear industry skyrocketed.