Even from its early days, the most famous parts of the town have been those where one could find a drink and, um, entertainment of the horizonal variety.  The Rocks, Kings Cross and Darlinghurst have all enjoyed nefarious pasts.

As the city has evolved so too have her red-light areas, driven by demographics, the economy and occasionally by planning laws. Summer decided to take a stroll through the city's steamier side, starting where it all began.

1. Circular Quay: From the very first day in January 1788, when the First Fleet landed at Circular Quay, sex has been a preoccupation in Sydney. On the first night of arrival,  marines were allowed a double issue of  rum "to make merry with women upon quitting the ship". It led to a drunken night of sex among the rocks despite Governor Arthur Phillip threatening dire punishments to his men.

Of the 1079 people on that first trip to Botany Bay, women convicts numbered 193, insufficient to prevent what Governor Phillip feared would be  "irregularities" occurring among the male population. Thought was given to bringing women from the Pacific to meet the need for female labour and companionship. Instead English authorities decided to kill two birds with one stone. The women's prison at Newgate was groaning with women sentenced to transportation for shoplifting, soliciting and theft. The solution was send the Lady Julian, sometimes known as "the floating brothel", which sailed for Botany Bay on July 1789.

On board were more than 200 women and 100 crew. As per custom , the crew were each able to take a woman during the voyage and by the time the ship reached Sydney Cove,  on June 4, 1790, there were a number of mewling infants to be fed and housed as well.

The colony, facing starvation, was far from delighted with the cargo of women, and some were shipped off to Norfolk Island as the grim battle for survival continued. But as we know, the colony flourished, and soon developed a flourishing sex trade.

2. The Rocks: For nearly a century the Rocks would be the main area for sexual services in the growing colony.  It was a place where "slang and vulgarity were mixed in lavish quantities, where harlots and riffraff, ex-convicts and the scum of all the oceans collected".

"Suez Canal" (supposedly a pun on "sewers")  was one of the most unsavoury places in Sydney in its time. It was haunted by prostitutes and larrikins, there for the brothels, sly grog shops and its opium den.

In contemporary Sydney, the area that was Suez Canal runs from George Street (between no 101 and 103) to Harrington Street. Walk along this route and imagine what it would have been like when a ship arrived in town, and the gangs of the Rocks Push marauded through the streets.

Now catch a bus to the corner of William and Palmer streets. The 324 and 325 and the 311 will take you there.

Tilly Devine's domain: By the end of the 19th century, Sydney had expanded eastward and to the south, with new slums emerging in Surry Hills and Darlinghurst. They were natural magnets for the poor, and by the 1920s the area had become Sydney's new red-light district.

There was also a thriving market in sly grog shops, thanks to strict regulation of alcohol from 1916 until mid-century. These laws prevented pubs opening on weekends and beyond 6pm.

By the late 1920s Tilly Devine - a brassy blonde whose life is immortalised in Larry Writer's book, Razor, and the Underbelly series of the same name - was running 18 bordellos in East Sydney, the Cross and  Woolloomooloo. She took prostitution to a level of organisation in Sydney not seen before. Her husband, Jim Devine, was busy getting the girls hooked on cocaine, the fashionable drug of the moment.  The Devines lived in a world of constant criminality, shootouts and wild parties. Tilly was charged and imprisoned many times with an increasing number of assault offences, including two years for slashing a man with a razor in 1925.

Our first stop is 191 Palmer Street, Darlinghurst, one of  Devine's brothels and the scene of wild parties, bloody shootings and Devine's 1945 wedding to Eric Parsons (and her shooting of him the same year).

Devine's rival in the grog and prostitution trade was Kate Leigh, a middle-aged woman who "had no fear of anyone".

Nows head along Chapel Street to Riley Street and walk up the hill towards Surry Hills. There is no longer a building at 104 Riley Street, but this is where Leigh shot and killed 'Snowy' Prendergast on March 27, 1930. The next year she gunned down Joseph McNamara. Her luck ran out in 1931 when she was busted with cocaine by Sydney's most famous policewoman, Lillian May Armfield.

Further along Riley Street, at the corner of Albion Street in the heart of Surry Hills, is Frog Hollow. This gully was once filled with flimsy tenements piled on top of each which were home to gambling, drug dealing, prostitution and the movement of stolen goods. In 2007 it was reclaimed by the city as public parkland.

On the same side of the street at 377 is Misty's, a working brothel, in the buildings once occupied by the legendary Touch of Class. Touch of Class belongs to a more contemporary era, but take note as you pass.

Now follow Riley Street until it ends and turn right into Devonshire Street. Pause when you get to 212 Devonshire Street, Surry Hills. Of more than 20 sly grog shops owned by Leigh, three were on Devonshire Street and the biggest of them ("Mum's") stood at number 212. Leigh lived in a tiny one-room apartment above this block until her death in 1964.

Now head back to Kings Cross to the famous Coca-Cola sign.

Kings Cross, the swinging decades: The Cross had had its fair share of night life during World War II as the area was dedicated to entertaining visiting American troops. By the '60s and '70s it was the epicentre of the sex trade. Sex workers plied their wares along William Street and Darlinghurst Road,  jumping into cars for a quick trip to a hotel room nearby. The Forbes Street steps, off William Street, were famous for transvestite hookers.

Prostitution was finally decriminalised in NSW in 1979, bringing brothels out of the shadows.On the corner of Bayswater Road and Darlinghurst Road, raunchy hostesses beckoned passers by from the Victorian verandah to enjoy  the Largest Bed in the World.  Behind more discreet facades, Kellett Street brothels operated next to French restaurants. The Largest Bed is gone, but there are still several brothels in Kellett Street.

While in Kellett Street,  take note of sign at the corner of Bayswater Road marking the August 1929 riots at the height of Leigh and Devine's rivalry.The 40-odd mobsters of the Leigh and Devine crews tore into each other with razors, guns, fists, boots, bottles and rocks. More than a dozen, from both factions, were badly wounded but no one identified their assailant to the police.

But perhaps the most famous brothel of the era was previously mentioned A Touch of Class in Surry Hills. Speculation about the ownership of the brothel has intrigued Sydneysiders since its opening in 1972. Despite penning the book Memories of A Touch of Class: Life in Australia's Best-Known Bordello in 1987, Zara Powell, its most famous madam, took to her grave the secret of who owned the establishment.

Rumours flourished that it was owned by a colourful Sydney business figure, and that the late billionaire Kerry Packer had a secret share. According to the tycoon's unauthorised biographer, Paul Barry, while there was no evidence to support this rumour, Packer once hired the entire place for the night so his polo-playing mates could enjoy a romp with "some good, clean girls".

After a period of decline, the brothel has been reborn as Misty's with its newest manager calling in the psychics to get rid of any lingering bad karma.

Modern brothels, sex in the suburbs: Brothels are now regulated under council planning laws with the aim of stopping them from being located too close to schools and places of worship. The result has been a spread of brothels to the suburbs, where the clientele is.

Legal and illegal brothels have proliferated in North Sydney, Chatswood, Artarmon , Crows Nest, Bondi Junction, Marrickville, Parramatta, Blacktown, Hurstville and Caringbah, says Chris Seage of Brothel Busters, a company used by councils to try and catch illegal "massage" parlours in the act.

Seage says it's not always easy for punters to know whether they are about to visit a legal or illegal establishment. He says the legal brothels are usually bigger and cleaner and meet council regulations for disabled access. The illegal ones are often masquerading as massage parlours and tend to be much smaller.

The big daddy of the legal brothel scene in Sydney is Stilettos, in Parramatta Road, Camperdown. It was owned by punter Eddie Hayson, but he filed  for bankruptcy a year ago.

Its current ownership is a little mysterious. The building was recently leased for 10 years to Psyche Holdings, a company controlled by businessman Tony Sherlock. But he told the Herald that his involvement was limited to the refinancing and he has nothing to do with the operation of the business. An 'independent third party' is now operating Stilettos, he said.

And then there is the internet, which has created a sprawling virtual market for sex, with the added advantage on anonymity.