I came across this storefront today, at the intersection of Rue Vivienne and Rue de Petit Champs. As a New Yorker, I immediately got excited it was a remnant of something vintage, with its signage retained but usage abandoned. But space is premium in Paris and there’s rarely an empty spot. Turns out, Dépôt Légal (legal deposit) is the requirement by a 1537 decree of King Francis I that “all printers and booksellers deposit a copy of any printed matter with the royal library as a legal or copyright deposit.” 
This law was expanded in the early 20th century (beginning in 1925) to cover publishers, and specific materials, including photographs. This pretty much means if you’re a French photographer, you’re legally required to submit your photos to the national library (Bibliothèque nationale de France-BnF). As this task is impossible, the reverse happens: the library chooses what to include in their collection. For fans of photographers Atget and Nadar, you can see original photographs in the reading room of the BnF. Works are often on display in the Gallerie Colbert, which is attached to the building shown above and next to the famous Gallerie Vivienne.
Photographer Mark Lyonrecommends submitting your work anyway even if you’re an amateur. It might just end up in the Pompidou collection, he says.
This and legal information about the dépôt légal process from the Encyclopedia of 20th Century Photography
How to Get There:
2 Rue Vivienne, 2nd arrondisement
Metro: M3 to Bourse, M7/M14 to Pyramides
Get in touch with the author @untappedmich.