Go to the centre of Edinburgh after dark and you can see the women start to colonise the district. The grey suits that are everywhere during daylight hours give way to multi-coloured miniskirts as the time arrives for a different kind of product to be traded.
One estimate says there are 2,000 prostitutes in the city at any one time.
But what happens when they get older and can no longer walk the streets? To put it another way, what happens to tarts when they pass their sell by date?
One answer lies behind an unremarkable brown door of a two-storey house in the city's poor Broomhouse area.
Push open the door and you walk into what is believed to be the world's first retirement home for prostitutes.
A fountain in its central court yard gives it the tranquil feeling of a home for pensioners in Florida.
Here all of the 30 women who have so far moved in are former workers in the sex industry.
The house is the idea of ex pimp and retired homosexual Jimmy Miller.
"It's taken me a long time to get this place opened ", he says. "We had to convince the local government and the police it was needed. But when I saw elderly women lying in the streets with nowhere to go, I knew I had to act".
As he talked to our Home Affairs correspondent , one woman called Edith shuffled by on a walking frame. Miller turned to our team and whispered:
"She's 88 and spent 70 years as a working girl. At her best she was charging merchant bankers £250 an hour. She could be yours for a fiver ".
At this point our reporter realised he had inadvertently become involved in somekind of vile Scottish Octogenarian sex ring. He made his excuses and left. As he was leaving an old dear, who was obviously being padded up for the night, shouted out,
"Careful of me Billy nurse, that's me fuckin' pension that is."