The name of the photo is "Boulevard du Temple" by Louis Daguerre and is the first photograph known to include humans. The photo had an exposure time of at least 10 minutes, so nearly nobody was around long enough to be captured—except a shoe shiner and his customer in the lower left hand of the photo.
The photo was actually a "Daguerreotype," which is a very complicated plate that is exposed to a silver-plated copper sheet to the vapour made by iodine crystals. The image was both reversed and had to be lit at a certain angle so you could see the smooth parts reflected something dark. This process was used regularly until the 1860s when it was replaced by newer forms of photography.
