Le Moniteur Bookstore
Filled with books on architecture, urban planning, landscaping and interior design, the Librairie Le Moniteur is one the largest specialized bookstores in Paris (and certainly the largest bookstore specializing in books on the topic that I've seen).
Inside, you'll find over 10,000 titles. Magazines, study materials, and professional reference volumes are upstairs, while the main floor is divided among the main thematic sections.
Paris is given special attention (and a separate section) in the store, with a selection of hyper-specialized quasi-travel guides featuring books profiling classic Parisian brasseries, giving a tour of the neighborhood around the Bibliothèque Nationale de France (François-Mitterrand), or narrating the history of the city's street signs.
Given the industry's global nature, the store stocks many foreign-language titles (at least 30%), primarily in English.
For a professional or simply the right type of amateur visitor (like myself), this store is a treasure trove.
Librairie Le Moniteur
7 Place de l'Odéon
Paris, France 75006