It began just over a decade ago as a social experiment aimed at getting prostitutes off the streets of the industrial city of Dortmund. With local council help, a 300-metre red light area was set up in the city's down-at-heel Ravensburger Street.
Containers nicknamed "Bird houses" were installed to facilitate the oldest profession. A Catholic-run advice centre set up near by and there were doctors' practices to help out. The project was so successful that delegations from throughout Europe came to inspect what became known as the "Dortmund model".
But, this week the city council bowed to overwhelming public pressure and shut down Ravensburger Street. "People are frightened about taking their kids to school," said the mayor, Ullrich Sierau. The city council says that the project worked well until 2007 when impoverished Bulgaria and Romania joined the EU.
After that, Mr Sierau says, hundreds of Bulgarian prostitutes arrived with the gangs who control them. There were shootings and big increases in organised crime. Dortmund now has about 700 registered prostitutes, many of them Bulgarian.
The Catholic advice centre sent a member of staff to Bulgaria to investigate. "Most of the women live in conditions far more miserable than those in Dortmund," was the conclusion. But Mr Sierau said: "We have to start sending Bulgaria a message that things have changed in Dortmund."