Stretching more than a kilometre through one of Zurich's most run-down areas, Langstrasse or "Long Street" certainly lives up to its name.
Unfortunately for the residents, it also lives up to its reputation.
For every clothes shop or jewellery store, there are three times as many brothels, strip-bars, erotic cinemas and sex shops.
By nine o'clock in the evening the street is starting to liven up: music blares from rival bars, residents give way to lone men and scantily-dressed women, and two of the scene's regulars are just beginning their trawl through the district's hot spots.
Hans-Peter Meier and Kurt Beck have been working for the city's vice squad for more than four years. And although they have other beats to keep an eye on, it's the nights on Langstrasse that tend to be the busiest.
"It's certainly different from the city's other districts," grins Meier as he steps off the tram to start his shift. "The whole sex scene is concentrated here in Langstrasse and it's all mixed in with the drugs scene too.
"Plus you get people from all walks of life coming here because there's always something to do or see - so yes, it's certainly special here."
The two men begin their patrol, checking out the windows opposite and above them for any sign of illegal activity. Beck is the first to stop.
"Up there," he gestures. "See that woman standing by the window? Underwear, red light, the lot. Now we just wait to see if she winks at me or beckons me in. If so, we can issue her with a fine."
There is little chance that the woman at the window will make such a mistake. Even in jeans and casual shirt, Meier and the rest of the vice squad team are well known to the city's prostitutes.
"It only takes them a couple of months to recognise our faces," Meier shrugs. "They even know our cars, and disappear as soon as we drive up. So it's enormously difficult to stop the illegal prostitutes. We would need to have a couple of new faces every week or so which just isn't possible."
A few steps further bring us to one of the city's 300 registered brothels. After knocking on the door, Meier and Beck are welcomed in like old friends by two scantily-clad North African women.
Their work permits are in order. Meier and Beck also use the opportunity to inform the women about the coming change to the law on window prostitution.
The conversation is not all one-way, however.
One of the women wants to know why the police don't concentrate on tracking down the illegal prostitutes who she says are undercutting the prices of the registered women. "We haven't had a single client for the past two nights," she complains.
The price for full sex can be as low as SFr40 ($30) on the street. Faced with rapidly falling incomes and increased competition, many prostitutes are agreeing to offer sex without a condom - attracting higher prices as well as higher risks.
Back in the registered brothel, the second woman is concerned that her family might find out about her current occupation and wants to know if her details are being kept in a computer or on paper. She also asks if she is entitled to any tax rebates since she only works two days a week.
After providing what answers they can, as well as contact numbers for the relevant officials, the officers head back out to inspect a much larger brothel.
"We always get trouble at this place," says Beck as we approach the four-storey building, its windows colourfully lit and entirely occupied by young women in underwear.
The officers make for the first floor and again warn the women, none of whom looks older than 18, that they will no longer be able to offer their services in such blatant fashion once the ban on window prostitution comes into effect.
As the police issue their warnings, customers continue to drift along the corridors and into the bedrooms. Some of the men hesitate when they see the inspectors, but none turns away. Unlike in the United States, the police can take no action against the men who pay for the prostitutes.
No fines are handed out in the brothel and the predictions of trouble seem misplaced. Five minutes after leaving the building, however, we are accosted by the owner of the building who thinks the police have been unfairly hassling "his girls".
He claims that the police are failing to apply the law uniformly and insists he will challenge any change to the law in court, unless the police start checking up on all the rival brothels.
While Meier listens to the complaint, Beck is busy handing out the first fine of the night.
This time there is no need to explain new regulations about window prostitution. The woman in question has been caught touting for business out on the street in clear violation of the law.
Smiling seductively as she pleads with Beck, the woman claims to be unaware of the ban on street prostitution. Although it seems like she could be play-acting, her annoyance seems genuine when she's handed the fine for SFr800.
Ways and means
Most of the prostitutes working on and around Langstrasse have found ways to conduct their business without roaming the streets or leaning out of windows.
Many hang out in known bars such as the "Sonne" pub on nearby Hohlstrasse. The establishment is even listed on the tourist office website, where it's noted for its live music.
When we visit, there is indeed live music along with live television coverage of a boxing match. But it's the presence of more than a dozen near-naked women that catches the eye of the exclusively male customers.
Those interested in taking things further will be invited back to a nearby three-star hotel which rents single rooms to the girls at the steep price of SFr100.
Neither the bar nor the hotel are breaking any laws, but they are clearly doing well out of the women's need to get off the streets.
Although the ban on window prostitution will soon give the police some new powers, Meier doesn't expect it to radically ease his workload or have a lasting impact on Langstrasse.
"Window prostitution is a problem, but it's not our biggest problem since it only goes on at a handful of the city's 300 registered brothels. The main difficulty for Langstrasse is that it's a residential quarter which has for decades also been an area for entertainment.
"I think it's impossible to bring the two together. One answer might be to have a designated area for the sex industry such as they have in Hamburg. But then the question will be where to put it."
But with residents and politicians insisting that Langstrasse will not be surrendered entirely to the sex industry, the police will continue to keep the prostitutes in check.
And with no long term solution in sight, Meier will continue to motivate himself with small comforts.
"Some officers start this job thinking they can change the world, but it's really a task without end. But we can often help the women, who are usually the weakest link in this lucrative industry. I just tell myself that things would be a lot worse if we weren't here."
swissinfo, Mark Ledsom in Zurich
There are around 3,000 registered prostitutes in Zurich.
Rising competition among the women has led to a sharp drop in prices.
Street prostitution is illegal in most areas of the city.
New legislation is now set to ban "window prostitution" as well.
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