Paris ? It began with a prophecy at Paris’ Saint-Sulpice church. An American visitor pressed a thick volume into the pastor’s hands and said, “My father, this book is going to cause you many troubles.”

The book was “The Da Vinci Code,” before it became a worldwide best seller. And the visitor’s prediction came true.

Dan Brown’s mystical thriller has spawned a mini-industry in European travel, with enthralled readers touring the locations in its plot to unravel its enigmas. From Scotland to France, they are scrutinizing old sites with new questions.

In Paris, fans ask: Are there really 666 panes of glass in the Louvre’s pyramid?

And at Saint-Sulpice, which features repeatedly in the novel, they come to snap photos of the church’s obelisk, the spot where the book’s murderous albino monk starts a quest for the Holy Grail. (The plot only gets stranger from there.)

For the church’s pastor, Rev. Paul Roumanet, this newfound fame has proved a headache. He’s fielded so many questions that he finally posted a sign to debunk the book’s claims. It starts, “Contrary to the fantastical allegations in a recent best seller …”

“It’s very unpleasant, everything that (Brown) scooped out of the trash cans of history,” Roumanet said in an interview.

“The Da Vinci Code” is a mix of code-breaking, art history, secret societies, religion and lore, all wrapped up in short, fast-paced chapters. Several other books have tried to debunk its contentious allegations — namely, that Jesus married Mary Magdalene and sired a bloodline.

The novel recently became the No. 1 fiction book in France, where intellectuals have dissected it on television and in the editorial pages. In the United States, the book is No. 1 on The New York Times best-seller list, where it has featured for 76 weeks.

The novel cites as many locations as a travel guide, prompting tourism Web site fodors.com to offer an online “Da Vinci” itinerary. The guide offers historical tidbits about the novel’s settings, from the Temple Church in London, to Rosslyn Chapel in Scotland, to the Ritz Hotel in Paris.

In London, even Madonna got the bug. British Tours Ltd. says it recently took the pop star and her husband, Guy Ritchie, to see London sites mentioned in the book.

The company’s marketing director, Jason Doll-Steinberg, likens the novel’s puzzles to the enigma of Stonehenge, a prehistoric site of huge stones arranged in patterns whose origins are shrouded in mystery.

“Look at Stonehenge at dawn, and why someone really wants to wake up in the morning (to see it),” said Doll-Steinberg of the site, another of the company’s destinations. “Mystery always appeals to people.”

In Paris, at least three tour companies are in on the fad. Clients, mostly Americans, pay handsomely for guided tours. Some cost as much as $370 per group.

Each company offers a different take on Brown’s novel. Art history lovers might try a tour from a company called Paris Muse. Its guides are graduate students who attacked the book like a research project. They came up with a 100-page glossary so they could be prepared for esoteric questions.

“When we were doing it, we said, ‘This is so much more fun than writing our dissertations,'” said the company’s founder, Ellen McBreen, a doctoral student at New York University who specializes in Henri Matisse.

Jean-Manuel Traimond’s Paris tour might appeal to people bent on debunking the book. As a Frenchman, he was incensed by Brown’s artistic liberties with French geography and historical facts.

“On page one I started to jump up and down with shock and indignation,” said Traimond, who works for the company Escape in France.

Brown “invents bridges that don’t exist. He puts trees where there are no trees,” Traimond said. “He claims Godefroy de Bouillon was the king of France, and he never was. … It’s like claiming Paul Revere was president of the United States.”

Then there are readers who seek out the sites themselves, or who simply find that the book subtly changed the way they think of the City of Light. Daniel Berg, an American engineer, found the book popping into his head as he sat outside the Louvre’s modern glass pyramid on a warm night.

The book claims there are 666 panes of glass in I.M. Pei’s pyramid. But everyone seems to come up with a different number: One official Louvre document on the Web put the number at 673, while tour guide Traimond says he personally counted 674.

Using mathematic equations, Berg came up with a count himself.

“I’d rather not say what it is,” he joked. That way, he can avoid the “Da Vinci” controversy.