“In the museum tour we are telling 100 years of history of Southeast Asia that can be viewed through the lens of this street,” he says.

Messner, son of late Austrian fine artist Ernst Fuchs, has the right qualifications for the job. His family runs the Ernst Fuchs Museum in Vienna, where he learned how to run such venues from an early age.

He relocated to Bangkok in 2001 and was quickly enchanted by the Patpong neighbourhood for its “authenticity and history”. He invested in a bar in the already packed go-go scene, and now runs the Barbar Fetish Club and Black Pagoda – just above the Patpong Museum on Patpong 2 Road.

Patpong took a while to earn its saucy reputation, having been established amid more reputable beginnings, and the Patpong Museum takes visitors down this memory lane.

Like many overseas Chinese, Tun Poon eventually entered Thailand’s rice trade, buying stock from the countryside to sell in the city. He noticed that rice farmers in the central province of Saraburi were below-average producers because of the limestone-rich composition of the soil. The land was not suitable for paddy fields, but was abundant in calcite, the perfect raw material for producing cement.

Tun Poon began mining the calcite to sell to the Siam Cement Company, which had been established through royal decree by King Vajiravudh (Rama VI). In 1930, Tun Poon was bestowed the title Luang Patpongpanich, or “Venerable” Patpongpanich, by Vajiravudh’s successor, King Prajadhipok (Rama VII), for his Saraburi-based enterprise. His business helped the Siam Cement Company – Thailand’s leading industrial conglomerate today – wean itself off calcite imports.

So began the rise in fortunes of the Patpongpanich clan, as the Patpong Museum reveals in its introductory room.

When he took control of his father’s property after his death in 1950, Udom cut a road through the land to connect the Silom and Surawong roads, giving birth to Patpong Road – which remains one of the few privately owned thoroughfares in the Thai capital.

Udom understood how such a move was key to infrastructure development and went about transforming Patpong into a modern business district – Patpong Road 2 was developed later – with shophouses, office buildings and Thailand’s first steel-framed car park.

Thanks to his supposed connections, many of Udom’s early tenants were US companies, including IBM, Trans World Airlines, Caltex, United Press International, the US Information Service Library and the US Chamber of Commerce, along with numerous European companies such as Shell, Dutch airline KLM and Belgian airline Sabena.

As the US geared up for the Vietnam war in 1965, other offices took root on Patpong, including those of Air America – the clandestine airline that ran America’s secret war in Laos – and other CIA-related operations.

The Patpong Museum illustrates the growing US presence with various memorabilia, including displays of Thai-language cartoon books published by the US Information Service Library to spread anti-communist propaganda throughout Thailand’s countryside.

One room features a miniature replica of the entire Patpong neighbourhood as it is today, with a red dragon’s head looming over it. The serpent, which weaves through the roof of the museum’s “historical” section, is inspired by a feng shui map of early Bangkok that locates the lucky dragon’s head in the Patpong neighbourhood, with its body curving through Chinatown and the tail ending up on Silom Road.

Visitors then leave the “historical” section and enter a mock-up bar room, with images of naked women dancing, and are offered an alcoholic drink. The bar room includes memorabilia from Patpong’s first go-go bar – the Grand Prix – opened by Vietnam war veteran Rick Meynard in 1967.

Meynard’s introduction of go-go dancing was a significant contribution to Patpong’s history. The practice of bikini-clad women dancing on an elevated stage somehow skirted the Thai legal requirement for a dance hall licence since the girls were dancing by themselves, not with men.

“So all the [go-go] bars in Patpong Road opened because you didn’t need a [dance hall] licence, only a liquor licence, and that’s the way it is even today,” Messner says.

Besides the Grand Prix, other old Patpong pioneer bars included Napoleon’s, Madrid, Texan Bar, Jockey, Max and Gaslight. All have now closed except for Madrid, opened by Khun Daeng in 1969 and now managed by her daughter, Jenny.

Madrid did a roaring lunchtime business in the late 1960s, and still offers popular specials such as the Madrid pizza, gumbo and a sizzling pepper steak. But today, especially for non-go-go bars like Madrid, surviving in the area can be a struggle.

“Business was good for the first 20 years, and then they opened the night-time street market [in the mid-1990s] and things went downhill,” Khun Daeng says, referring to the string of stalls that runs the length of Patpong offering cheap goods ranging from clothing to pirated DVDs. The market, which opens at 6pm, attracts hordes of tourists, but detracts from the discretion some bar-goers seek.

Contrary to popular misconceptions, Patpong was never a magnet for US troops on rest and recuperation (R&R) tours during the Vietnam war.

“Only officers came to Patpong during the Vietnam war,” Khun Daeng recalls. “All the GIs went to New Petchburi Road [also in Bangkok],” which was then nicknamed “The Golden Mile”.

When the R&R tours dried up after the Paris Peace Accords treaty was signed in 1973, so did the Petchburi bar scene.

“Patpong had the advantage that it was in the central business district,” says Norm Smith, a long-time Bangkok resident and publisher of the Bangkok Eyes website.

The last room in the museum is the X-rated section, offering a glimpse of Patpong’s more dubious attractions. Most memorable is the image of a young woman from whose nether parts pop out ping-pong balls, and a photo test featuring transvestites versus real women. Visitors take a guess, then lift the photo to reveal the actual gender.

Photos visitors might want to forget include the “razor blade” show, similar to the ping-pong show but with different props.

Messner, who is married to a Thai woman with whom he has had five children, would be remiss to exclude Patpong’s go-go bar scene in his museum, but he has attempted to keep the displays “couple friendly” (the museum is X-rated for visitors aged 18 years and older).

He claims the museum has earned the unofficial approval of the Patpongpanich clan, which still owns the two roads and all land in the Patpong neighbourhood.

“They came to take a look [before it opened] and they brought me flowers afterwards,” Messner says. “They were worried it was just going to be about go-go bars.”