For 20 years she thought it was true. "And then, poof, I discovered it was a big fat lie," says Isabelle Demenge, in her wonderfully Parisian accent.
The lawyer-turned-writer was talking about her gap year in India, long before she was a married mother of three boys and publishing children's books in Hong Kong. A guide at the Taj Mahal in Agra had told her a bogus history of the marble mausoleum, which stayed with her until recently.
"Shah Jahan built the Taj for his third wife, Mumtaz Mahal, who died in childbirth. This guide told me Jahan wanted to build a copy, in black, on the other side of the river connected by a silver bridge in her memory."
It's a romantic yarn but, as Demenge discovered while researching one of her books, it is simply the fantasy of a 17th century French jeweller who peddled the tale. "It's such a beautiful idea, but it's not true," she says.
Demenge uses urban legends such as these to engage the interest of young explorers through her new series of travel books for children.
Her Leap and Hop guides try to make educational travel fun and have so far covered destinations which include Cambodia, India and Sri Lanka.
Also featuring her own photography, the colourful guides work as scrap books for children on holiday with their parents in destinations more challenging than a typical Thai island resort.
The books ask young readers to take selfies in front of famous landmarks, to draw the country's currency and list their favourite and worst national dishes. Other sections supply historical information. Demenge spends months doing research before getting her children to test out the games and quizzes on holiday.
"If they are too easy, I start again," she says.
The idea for the books came to Demenge while she was still living in New York, working as a banking lawyer.
"Before we had children, my husband and I had loved to travel. When the youngest of our boys was eight months old, we decided to go on holiday again and took them to Mexico."
She draws a deep breath and winces at the memory. "It was very, very hard."
Soon after, her husband was asked to set up the Hong Kong branch of his law firm, Proskauer Rose, and the couple relocated.
"It was 2008," she says, "not such a great time for a banking lawyer, so I took a never-ending break from the legal profession."
For Demenge, who started globe trotting as a toddler with her parents, Asia presented a wealth of new travel possibilities - and having three boys under the age of 10 was not going to stop her.
Their first family trip was to Bangkok and then Cambodia. "Friends back home in France said, 'Why are you taking your children to these weird places? They won't remember it.'
"But I think it's important for children to know that things are not the same everywhere. Discovering other universes helps you understand your own better."
Besides, Demenge and her husband were determined to see the world.
Demenge wrote her first book for the family's Cambodian holiday. "I gave it [to the children] on the plane. They started with the word search then flicked through and found things about the country they were interested in," she says.
From Angkor Wat to the Silver Pagoda, the book engaged her boys in the historical sites normally only the adults in their family would want to visit. What's more, the book educated them on the country's history, from French colonisation, through the Khmer Republic and to modern-day Cambodia.
"When we got back, friends starting asking for copies of the book," Demenge says. "I realised I could be onto something."
The lawyer turned housewife found herself with the new occupation of children's book writer. "I'd written a lot of contracts before, but never fiction," she says.
Each book takes her about three months to research and write, and the texts are kept under lock and key until the family gets on the plane.
"For our next holiday, the boys don't even want to know where we're going. They'll find out when I give them their book at the airport."
As well as penning the guides, Demenge is also heavily involved with the Hummingfish Foundation, a charity founded by photographer Daniel Groshong to support community-based ecotourism in poor countries.
Groshong had spotted a photo collage that Demenge had made of her children while on assignment at the launch of her husband's Hong Kong office, and the pair met for coffee.
"He had 20,000 million ideas a second and needed help to get his thoughts together. I told him I'd do anything but the legal work. Of course, that's what I ended up doing most," she says.
"Originally, the idea was to use photography to market countries that have amazing natural beauty that is not used to its full potential."
Groshong started in East Timor, a country of just over one million people. He photographed its natural resources and helped the country participate in the 2010 World Expo in Shanghai - the first time the country had taken part in such an event as a free nation.
"Daniel spent time in [East] Timor when it was becoming independent and made the first coffee table book of [the country]. Those pictures are beautiful, and have been given as a state gift from the government to ambassadors around the world."
Today, the foundation focuses primarily on green projects. Demenge is still active in its running and is also busy writing her next Leap and Hop book about a destination she knows very well - Hong Kong.
Has she been surprised by her literary success?
"Yes," she says. "But I think many parents want to travel. When you have children life doesn't stop."
While lounging by the pool can be great, Demenge believes parents also want to experience a country's history and culture, which, in turn, opens their children's eyes.
"Take India, for example. In any restaurant, they assume you're vegetarian and if you're not they say, 'Oh, are you non-veg?' For them, non-veg is the exception.
"You're never too little to understand that you're part of something bigger."