While working on a book about Los Angeles's sewers, author/historian Anna Sklar stumbled on a cache of thousands of amazing photos taken by the LA City Engineer's office as far back as the 1890s. Now, thanks to the Los Angeles City Historical Society, more than 600 photos from those LA City Archives have been uploaded to one awesome, searchable website. (And there are more are on the way, Sklar told LAObserved a few weeks ago. You can read more about the discovery at KPCC.) The collection is full of incredible shots of the developing Los Angeles of the 1920s and 1930s, with scenes of bridges, roads, sewers, and other infrastructure being built and scenes of the landscape after they've been destroyed. A quick perusal (or click of the "random images" button) might show you Los Feliz Boulevard or the streets of present-day Westwood when they were nothing more than dirt paths; the archive also has plentiful documentation of the 1938 floods and the destruction they left behind, from Malibu to the San Gabriel Valley. We picked 12 standout images, but this is definitely the kind of site you could lose an hour or two browsing through.