I started reading "When Paris Went Dark: The City of Light under German Occupation, 1940-1944" by Ronald Rosbottom. What an excellent book! Well-written, lots of images, fascinating and tragic at the same time. Makes me want to return to Paris and walk down all the streets where these events happened.
Another excellent book, which of course I didn't read until after I returned from the city, is "The Greater Journey: Americans in Paris" by David McCullough. He writes nonfiction like it's fiction, easily getting inside the heads of historical figures and making them accessible to readers. It's been a while since I read this book but I think he focuses on the time period of ca. 1850 to 1900.
Any recommendations for great nonfiction reads about Paris?