In what cities can "red light districts" be found? Give examples of where this approach has been or is currently being used.
The most famous red light district in the world can be found in the De Wallen district of Amsterdam, Netherlands. Red light districts are, of course, areas where known prostitution can be found. In Amsterdam, De Wallen is an area located in the oldest part of the city, and the red light district there encompasses several blocks where women--often dressed in lingerie and sitting in windows or glass-paned doorways--legally offer their sexual services for a price. Prospective customers can view the women and converse with them, presumably before deciding upon a price for services rendered. The area is so renowned (or infamous) that it has become one of the leading tourist attractions in the city.
Red light districts exist in other parts of the world. In Hamburg, Germany, the Reeperbahn is a legally regulated area which boasts many prostitutes. Illegal red light districts also exist in Asia, particularly in Thailand.