Amsterdam Red Light District

But the district is a magnet for petty criminals and, authorities believe, human traffickers, drug lords, and mobsters who take advantage of the situation to launder money. Prostitution is legal in the Netherlands, and coffee shops are licensed to sell small amounts of marijuana. But prostitutes don't have cash registers and drug vendors don't give receipts, making it easy for them to launder money for crime lords.

Authorities said they hope to detect and prosecute money-laundering by building a national database of tax returns and other information that would allow them to compare café and brothel owners' legal income to assets they hold around the country. And local authorities promised to enforce other existing laws more strictly.

The aim is simple: to get rid of the criminal part of the Red Light District.

Amsterdam has been conducting its own cleanup program for nearly five years, using a 2002 law that forces business operators to disclose detailed accounting in order to have their licenses renewed.

Last year, the city ordered the closure of one-third of all brothels in the Red Light District that were unable to comply. But Amsterdam's District Court blocked the closures while brothel owners fight the decision. That case is pending .

In response to negative publicity from the ongoing crackdown, a number of prominent bars and brothels in the Red Light District have joined together to hold an annual "Open Day" where visitors are invited, free of charge, to have a look at what goes on inside.

Normally, doors are closed and bouncers strictly prohibit photographs even outside the building.

The first two open days last year and this year drew large crowds, mostly of middle class Dutch women and men who would ordinarily be too shy or embarrassed to be seen in the area.