The Sathorn Unique building remains a shell in Bangkok. The 49-storey high-rise was supposed to feature luxury condos for hundreds of newly affluent Thai families, but it was abandoned unfinished when the 'Tom Yam Kung' crisis struck. (Photos by AP)

The 49-storey Bangkok high-rise was supposed to feature luxury condos for hundreds of newly affluent Thai families, but it was abandoned unfinished when the Asian financial crisis struck in 1997.

Now called the "Ghost Tower", it's a monument to mistakes made and an object of curiosity to a steady stream of visitors.

Sathorn Unique, named after the up-and-coming neighbourhood next to the Chao Phraya river it towers over, draws dozens of foreigners daily who come to gawk at the decrepit, stained concrete edifice. It's home not to Thai yuppies, but to bats, birds, weeds, trees and a black-and-white spotted cat, seen prowling one afternoon on a seventh-floor balcony.

"The only way is up," reads graffiti scrawled in chalk on the fifth-floor landing, an ironic reminder of the building's aspirational past.

Weeds grow on a balcony overlooking the Chao Phraya river.

Near the building's entrance sits a ramshackle homemade spirit shrine. A yellowing poster of the late King Bhumibol Adulyadej, clad in royal regalia, is plastered above ashes of spent incense and opened bottles of fruity Red Fanta -- the ghosts' favourite drink, according to watchman Suwaschai Dadaelor.

In the booming 1990s, Bangkok's skyline was surging skyward and studded with construction cranes.

Architect and property developer Rangsan Torsuwan was flush with cash from selling ornate, high-rise condos along the beach in Pattaya. He drew up blueprints, cleared the land and made millions of dollars pre-selling the condos.

Then came what Thais call the "Tom Yam Kung" crash, referring to the sour-and-spicy soup. It started in Thailand when the overleveraged government unexpectedly devalued the baht. Investors rushed to pull their money out as quickly as they could, setting off a regional financial crisis.

About 500 big construction projects -- from shopping malls to elevated railways -- came to a screeching halt. Some later resumed, but not this one.

At 185 metres, the structure is among the tallest abandoned skyscrapers in the world, after North Korea's 105-storey Ryugyong Hotel, which has been under construction since 1987.

Unattached toilets sit in an open room of the 'Ghost Tower'.

In the Ghost Tower's heyday, hundreds of tourists flocked daily to the urban ruin, paying a 200-baht bribe to stumble over piles of bricks and bags of cement to stage photo and YouTube shoots and hold boozy parties on the rooftop.

"The photos look so dope," says Sorcha O'Malley, a tourist from Ireland spotted one afternoon snapping pictures from a side alley. She looks up. "I really want a photo up there, you know?"

"Even when I was walking here my heart was kind of pumping already," German visitor Annikha Mahnke chimes in. "It's such a big adventure to go up there."

In April 2015, two 20-something parkour runners posted videos of themselves on YouTube ducking and weaving through the building, somersaulting off columns and dangling off balconies. Their footage went viral, drawing thrill-seekers and urban explorers.

For Mr Rangsan's son Pansit, who is now in charge of the building, that was the last straw. He locked up the stairwells.

"I only feel worry," he says. "This is not a complete construction, and it's very dangerous to let people to go up there."

A few years ago, a 30-year-old Swedish man, Stig Johan Kristian Hammarsten, hanged himself on the 43rd floor. His rotting corpse was discovered weeks later, cementing the building's reputation as a "ghost tower".

"Pray to the spirits" pulsates in neon orange spray paint, in Thai, on the 43rd floor.

Mr Suwaschai, the guard, says he pays his respects daily to appease the ghosts that haunt him at night. One peered at him from behind a column, he says, a shadowy, powerfully built labourer with slick black hair wearing nothing but a loincloth. Another grabbed and levitated his body once when he was sick.

Empty beer bottles and graffiti litter the roof of Sathorn Unique.

A Thai-Taiwanese couple stopped by to take selfies in a lift shaft and later found other faces in the photos, Mr Suwaschai says, pointing insistently to shadowy figures in a picture's background. "This is a true story, I'm not making stuff up."

A famous cinema was razed to make way for Mr Rangsan's folly, but rumours that it was built on an ancient cemetery have added to its mystique.

The property has been mired in a complex lawsuit for years, and it looks unlikely that anyone will demolish it anytime soon. Inspectors say the reinforced concrete structure is still fundamentally sound despite weathering decades of storms.

For now it serves as a support for two 18-storey billboards: one advertising Pepsi and the other the iPhone 7.

For Thais, the tower is a reminder of lessons learned.

On one recent February afternoon, a crowd gathered on the Ghost Tower's ground floor for a seminar. The topic: the tower, the financial crisis and the 20 years since.

"This building is important because it is a symbol," said Rames Promyen, director of the National Discovery Museum Institute.

"It serves as a reminder to ourselves -- a reminder of how to better prepare for future crises, and how to strengthen ourselves." 

The view of the river and skyline was a selling point for Sathorn Unique.