A visit to the temples of Angkor Wat, followed by a stop at an orphanage, are part of the travel experience for many of the more than four million tourists who come to Cambodia every year.
What they do not realise is that the impoverished Southeast Asian country is in the grip of a boom in orphanages, many of them unlicensed, with no safety checks, few real orphans, and subject to growing concern about neglect and abuse.
Most of Cambodia's orphanages are financed by private donations from abroad, but no one knows exactly how much money flows into the country or how many centres there are.
"It's hard to gauge because many orphanages are not transparent about their accounts, but it's a pretty safe guess that it's a multimillion dollar business," said James Sutherland, communications coordinator at Friends International, a social enterprise that works with disadvantaged children.
Orphanages are expanding because Cambodia lacks a social welfare network to support poor families, its institutions still struggling to recover from the devastation caused by dictator Pol Pot's genocidal regime in the late 1970s.
Between 2005 and 2010, the number of registered orphanages rose 75 percent to 269, housing almost 12,000 children, according to the United Nations children's agency UNICEF.
Since then, hundreds more have sprung up, usually run by private individuals or faith-based organisations, many of them from the United States or South Korea.
One of the largest is Foursquare Children of Promise, a U.S.-based group dedicated to "building the kingdom of God", which runs over 100 residential care facilities in Cambodia.
FCOP was unavailable for comment.
A UNICEF report found that in many orphanages the standard of care is extremely poor, although Cambodia introduced minimum standards in 2006.
UNICEF's Cambodia country representative, Rana Flowers, said a lack of registration and of enforcement of minimum standards put children at risk of neglect and abuse.
"I consider this to be a humanitarian emergency," Flowers told the Thomson Reuters Foundation.
"This is a growing industry with little regulation, so anyone can open an orphanage to the detriment of thousands of children."
The chances that a well-meaning tourist's cash will help a real orphan are slim as around 77 percent of children in orphanages have at least one living parent, according to UNICEF.
Many parents in poor rural areas see little choice but to place their children in orphanages because they cannot afford to send them to school.
The true scale of the orphanage problem should become clearer when a survey carried out by the Ministry of Social Affairs and aid groups is published later this year.
"The number is likely to be closer to 600, which shows that this problem is out of control," an aid source, who requested anonymity, told the Thomson Reuters Foundation.
While the data is not directly comparable because the survey will include un-registered orphanages, it shows the government is struggling to contain the boom, despite its stated policy that residential care should only be a last resort for children.
The government wants to stop more orphanages from opening and has promised yearly inspections, but it has only 30 inspectors, making it hard to monitor the industry.
"We don't encourage more units to open," Oum Sophanara, director of the government's child welfare department, told the Thomson Reuters Foundation.
The government inspected 228 residential care units last year housing a total of 11,014 children. Only 22 of those are run by the government.
"There are many more units that we have not been able to find," Oum said.
Since 2011, the government has shut down 11 orphanages that failed to meet its minimum care standards.
The growth in orphanages matches an explosion of tourism in Cambodia, where the number of foreign tourists has shot up to 4.5 million last year from less than 200,000 in 1994.
Most of them go to Siem Reap, a town close to Angkor Wat in one of the country's poorest provinces, and the centre of "orphanage tourism" in Cambodia.
Orphanage tourism is prevalent in other parts of Southeast Asia too, such as northern Thailand where some centres charge volunteers up to $400 a week to spend time there.
It is also increasing in Myanmar as tourist numbers rise, prompting the government to commit itself last year to a moratorium on opening new orphanages.
Friends International is working with other charities to raise awareness through the "Don't Create More Orphans" campaign, launched in February.
"It is getting a lot of traction but many tourists are still unaware how damaging orphanages are," said Sutherland.
There is a growing view in Cambodia that growing up in a residential care centre is damaging for a child's development and that children need to be loved and cared for by one or two familiar adults, rather than strangers.
M'Lop Tapang is one of a growing number of community-based organisations that provide shelters, education and vocational training with the aim of bringing children back to their families.
"Every child needs to have a family to belong to," M'Lop Tapang director Eve Sao Sarin told the Thomson Reuters Foundation. "When a child lives at home, they're in a community and have a much better chance to learn essential life skills."
M'Lop Tapang does not let tourists or volunteers come to its facilities in the seaside town of Sihanoukville, except for its Sandan restaurant where it trains street children to become chefs and waiters.
"We don't think it's a good way to fund-raise or promote our work," Sarin said.