It is a side of Bangkok that tourists seldom see: Not far from the Buddhist temples, glitzy malls and go-go bars, is a neighborhood of shacks and squat homes in narrow alleys with open gutters in the city's oldest and largest slum.
Klong Toey is home to about 100,000 people, mostly rural migrants from northern Thailand who came to the city for jobs.
While many live in brightly painted homes with motorbikes parked outside, others live in shacks without running water or electricity.
It's not that different from the days when 66-year-old Prateep Ungsongtham was growing up there with her six siblings.
"The number of people living here has doubled since the time I was a kid – yet their condition is not that much better," she said in an interview at her Duang Prateep Foundation in Klong Toey.
The neighborhood's residents run Bangkok's largest wet market, and work in the nearby port. They also live under the threat of eviction in a fast-gentrifying city keen to be seen as modern.
"There are few facilities, no one has titles for their homes, and evictions are always a threat," said Ms. Prateep, who has been advocating for the rights of slum dwellers for five decades.
"It's always a fight."
Prateep's father was a fisherman who came to Thailand from China. Like other migrant workers in Bangkok, they lived in a shack of wood and tin, perched on stilts for some protection from rising waters during the monsoon rains.
With no birth certificate, Prateep was denied admission in the public school nearby, and went to a private school for four years. She had to drop out at age 12 when her parents could not afford to pay the fees, and she had to begin working.
Prateep worked on the docks like hundreds of other children from Klong Toey, scraping rust off ships' hulls and doing other odd jobs. She went to a night school with money she set aside.
"So many of the children who were working could not read or write; even many of the grown-ups could not read. I did not want to be like them, and work in the harbor all my life," she told the Thomson Reuters Foundation.
"But I also wanted to help them. If there was an accident, they had nothing to fall back on, there was no support."
To supplement her income, she and her sister began minding neighbors' children while they worked.
In the space below their home, Prateep and her sister kept the children engaged by teaching them songs and the alphabet. They charged one baht per child, the equivalent today of about 5 US cents.
Soon, dozens of children came to the One Baht School, as it came to be known. It was their only option as most schools refused to enroll them because they did not have birth certificates, Prateep said.
With some 80 kids crowded into the school, Prateep's family received an eviction notice from the Port Authority. But officials relented as support for her school grew.
The Port Authority gave her a site for a school, which the Bangkok Metropolitan Administration recognized a couple of years later. On Prateep's insistence, it also ended its policy of barring children without birth certificates from school.
"For the poor, the only way out of poverty is education," said Prateep. "But if you do not have an ID, if you have to keep moving because you are being evicted, how do the children get an education?"
She said her family was forced to move six times when she was a child.
"The port authorities would just say, 'We need this land,' and they would put all your belongings outside, and tear down the shack."
Prateep began educating Klong Toey's residents about their rights, including resisting evictions.
Still, while many residents have lived there for three generations, city officials are reluctant to upgrade facilities because they do not want them to stay put, she said.
In 1978, Prateep received the Ramon Magsaysay Award for public service. She was 26 years old, among the youngest recipients of the award, known as the Asian Nobel Prize.
Her citation said Prateep was recognized for "bringing learning, better health, and hope to impoverished children otherwise denied services."
Prateep said she moved out of Klong Toey years ago after she got death threats from the drug gangs there.
The push to tear down slums and clear streets of vendors continues today, with Prime Minister Prayuth Chan-Ocha saying the poor should move from the city's slums and the riverside, so the areas can be made over into parks and walkways.
Prateep and other campaigners oppose the city's policy of resettlement, which they say cuts the poor from their social networks and limits their ability to make a living.
"Most Asian cities are wealthy now, and they want to be Smart Cities with no room for the poor," said Somsook Boonyabancha, a founder of the advocacy group Asian Coalition for Housing Rights.
"Instead, why not enable the community with funding to be part of the solution? Cities are not just about infrastructure, they are about people," she said.
On a recent weekday morning, Prateep, a trim figure with her salt-and-pepper hair worn short and a colorful scarf knotted around her neck, dropped in at a kindergarten that her foundation runs in Klong Toey.
Children dressed neatly in pink and red crowded around her, testing their newly learned English to wish her "good morning," and ask, "how do you do?"
After demonstrating a science experiment and sampling their grilled vegetables, Prateep walked briskly through the narrow alleys, greeting an old man seated outside his home, and checking on a vendor stringing flowers.
"Some things have improved here since my childhood, but poor migrants coming to the city still have nowhere to go," she said.
"Their lives are still insecure."
This story was reported by the Thomson Reuters Foundation.