It began as a book. It has grown into an empire.

That empire, built on the best-selling novel 'The Da Vinci Code," is bound to explode even further this weekend with the opening of the movie, which premiered Wednesday at the Cannes Film Festival in France.

The film joins scores of spin-off books, TV specials, documentaries, board games, video games, jewelry, Parisian tours, travel guides and even a diet in the growing Da Vinci dominion.

“'The Da Vinci Code' is not just a story. It’s a lifestyle,” said pop culture expert Robert Thompson, a professor at Syracuse University.

The Dan Brown page-turner, hinged on the idea that Jesus Christ and Mary Magdalene were married, caused a stir practically from the moment it hit shelves in 2003, staying on the hardcover best-seller list for most of the three years since. In all, the book has sold more than 60 million copies worldwide.

The edge-of-your-seat thriller has managed to intrigue a wide array of readers with its conspiracy-theory plot, blending of fact and fiction and mix of religion, art and puzzle-solving — not to mention romance.

Prognosticators believe the big-screen version of Brown's story — directed by Ron Howard and starring Tom Hanks, Audrey Tautou, Ian McKellen, Paul Bettany and Alfred Molina — will not only be a smash on its own, but will also fuel the hype and the offshoots.

"It will only enhance it," said Paul Dergarabedian, president of box-office tracker Exhibitor Relations Co. "The book has already captured the imagination of the world. [The movie] is on track to do some big, big numbers. Certainly this film has more than enough behind it to ensure $100 million gross and above."

It isn't the first time a book has generated such a sensation and has grown into much more than words on the page; J.K. Rowling's "Harry Potter" enterprise is case in point. But it certainly isn't an everyday occurrence that a novel, especially one written primarily for adults, becomes so huge.

At the center of Brown's story is the old theory that Jesus Christ and Mary Magdalene were married, had children and have descendants. "The Da Vinci Code" characters are all on a mission to either keep that a secret or expose it to the world as the truth.

Brown's craftily woven tale has been the inspiration for countless books about that hypothesis, Mary Magdalene, Christ, the Catholic Church, Christian history and the Gospels, among other related topics.

Some of the religious theory books that have profited were written long before Brown's novel was, but have just gotten more play since "Da Vinci Code" mania hit. Several were used in his research.

Among them is "Holy Blood, Holy Grail," the focus of a plagiarism case against "Da Vinci Code" publisher Random House. The plaintiffs lost the case, but "Holy Blood" co-author Michael Baigent has come out with another related book this year called "The Jesus Papers," which claims Christ survived the crucifixion.

Other newly published or reissued "Da Vinci Code" byproducts are about Leonardo Da Vinci himself, art, the Louvre Museum and symbology.

"You walk into a Barnes & Noble or a Borders and you get entire tables and sometimes multiple tables of not only 'The Da Vinci Code' but 'Da Vinci Code' titles, some of which are churned out to capitalize on this and some of which are moved from the art history [and other] sections to these tables in the front," said Thompson.

There are also copycat novels. And then there are the books that attempt to crack "The Da Vinci Code" itself.

"Secrets of the Code" by Dan Burstein is one such spin-off, which decodes "The Da Vinci Code" and expounds on the novel's theories in interviews with leading scholars.

"For all the people who found 'The Da Vinci Code' really interesting but want to go further and learn more, we tried to provide the raw materials," Burstein said.

A host of travel guides have stemmed from the best-seller, too. Walking and minibus "Da Vinci Code" tours in Paris take visitors to the various places the novel's characters go in their quest to solve the mystery.

"Every major travel publisher has a travel guide book to 'The Da Vinci Code,'" Burstein said. "More are coming."

In all, at least 90 different titles in a variety of genres have seen better sales because of the popularity and success of the Brown book, according to USA Today.

Though the publishing world has been at the center of much of the growth of the "Da Vinci" kingdom, television has also cranked out its share of offshoots in the form of documentaries and specials on everything from Jesus, Mary Magdalene and church history to art, code-cracking and the secret societies in the novel.

For more playful fans, a "Da Vinci Code" video game and board game are on the market. And for fashionistas, jewelry designer Michelle Ong created a special pendant from the "Fleur de Lys Cross Key" featured in the novel to help promote the film in Hong Kong.

There are even diets and exercise regimens — described in the books "The Diet Code: Revolutionary Weight Loss Secrets from Da Vinci and The Golden Ratio" and "The Da Vinci Fitness Code" — born out of the madness.

"The Diet Code" outlines a meal plan using the mathematical principles of the so-called Golden Ratio employed by Da Vinci and featured in Brown's story.

"The Da Vinci Fitness Code" details the history of weight training, claiming it dates all the way back to the Stone Age and the Renaissance when people were lifting not barbells but stones and rocks used in daily life.

And even with lukewarm reviews and international protests and boycotts of the film, the craze isn't showing signs of letting up. All of Brown's novels are being made into films, and the paperback version, just released in March, is flying off shelves almost as fast as the hardcovers have.

"I think there will be a ton of licensed products coming," Burstein said. "This stuff is going to be with us for the next decade. It's possible that 'The Da Vinci Code' may be a once-in-a-lifetime or a once-in-a-generation experience."

As for whether those who have profited from Brown's heyday should feel guilty about piggybacking off someone else's success, Burstein doesn't think so.

"Dan Brown himself took all his ideas from [other people]," said the "Secrets of the Code" author. "For the same reason he has every right to write a novel based on all these others' work, we have every right to write books about that novel. These ideas are the common property of humankind."