Red light district: A neighbourhood containing many brothels.
Radha's excellant post on 'Kids with cameras' brought to light the phrase red-light district. I spent some hours in this district last night. Time spent into the term's origin, that is.
Version 1: Brothels once advertised their presence by burning electric lights covered with red shades or glass in their windows. This led to the Americanism 'red-light district' for an area know for its houses of prostitution, the term first recorded in the late 19th century
Version 2: The term "red light district" is said to have originated with early railroaders. The men carried lit red lanterns when they left the train so in case of an emergency the crew caller would be able to find them. These lanterns were left outside bordellos when crew members stopped to pay the ladies a visit and sometimes were brought inside to be placed in a window.
A railwayman's lit red lantern left sitting in front of an establishment could just as easily have come to signify a saloon or a barber shop as it did a brothel. On the other hand, the lit red lantern quietly residing outside a nondescript building of unclear purpose could well have come to be seen as a discreet advertisement of what was for sale within.
Version 1 gets a confirmatory endorsement in Holland, where window prostitution is legal. The question "How many windows are there in Amsterdam?" prompted a ground survey in July 2006 which put the count at 506. The picture above is worth a thousand words really.