De Wallen, also known as Walletjes or Rosse Buurt, is the largest and best-known red-light district in Amsterdam, a major tourist attraction. It is a network of alleys containing several hundred tiny one-room apartments rented by female prostitutes (and some ladyboys) who offer their services from behind a window. It also has a number of sex shops, sex theatres, peep shows, a sex museum, a cannabi