PARIS - St. Sulpice on the Left Bank of the Seine is a regal 17th-century church but has never been much of a tourist draw.
After all, it's not easy competing against Paris' many crown jewels: the Louvre, the Arc de Triomphe, the Eiffel Tower and Versailles. Just within the neighborhood, the church of St. Germain des Pres is better known.
It took a recent book to make St. Sulpice something of a must-see. The church is a centerpiece of The Da Vinci Code, the phenomenally popular novel by Dan Brown. The author's choice of venue has turned this old church into a favored starting point for tourists.
The Da Vinci Code centers on a modern-day search for the Holy Grail. It follows the fictitious Harvard professor Robert Langdon, an expert in ancient symbols, and Sophie Neveu, granddaughter of the Louvre's chief curator.
The two spend a long night escaping from a locked Louvre, speeding around the Arc de Triomphe, following the trail of obscure clues Sophie's grandfather leaves behind when he is murdered in the book's prologue. Along with his day job at the Louvre, Sophie's grandfather was the leader of a mysterious religious clique that jealously guards its knowledge of the whereabouts of the Holy Grail.
His vocation and avocation apparently bestow upon him the knowledge and good taste to secrete his clues -- and even the false leads he creates to confuse his enemies -- in some of Europe's better touring spots: Paris, London, Rome and scenic churches, temples and chateaus across the continent.
Chateau de Villette, 25 miles northwest of Paris, is one of them. In the book, the 17-bedroom chateau from the 17th century is home to Leigh Teabing, an eccentric English expatriate who creates an evil scheme that is the core of the book's plot.
The Chateau de Villette, where filming for the movie version (due in 2006) took place, has stopped doing short tours. But it still offers a tour of Paris Da Vinci sites, with five nights at the chateau -- for a hefty price.
Author Brown's eye for detail and unique landmarks have made The Da Vinci Code more than just an entrancing mystery novel. It's an intriguing guidebook, too.
Tour companies have taken note. They have built a mini industry of Da Vinci tours in Paris, London and other sites throughout Europe.
On the walking Da Vinci Code tour through Paris, the St. Sulpice obelisk is a highlight, and a good place to start.
On the floor is a brass line -- the "Rose Line" in the book -- that serves in life as in the book as a kind of Greenwich on the Seine, a meridian line by which Parisians of the 18th century set their clocks.
And there, in the transept of the church to the left of the altar, is the piece de resistance: a marble obelisk more than 30 feet tall that once served as a kind of calendar. When the sun's shadow hits certain symbols on the obelisk, it marks the summer and winter solstices.
The point where the "Rose Line" hits the obelisk is precisely where Sophie's grandfather hid his most important false clue.
The tour I took was organized by Paris Walks, a firm owned by a British couple that focuses its business on themed walks of Paris. Guided tours last about two hours. Several books are available for people who prefer self-guided walking.
Many of The Da Vinci Code sites are on the Left Bank of Paris, one of the world's great touring districts. But it is The Da Vinci Code sites that make the walk unique.
The church of St. Germain des Pres, for example, is a burial site for Merovingian kings -- objects of one of the book's most controversial fictions, that this line of French royalty known as the "Do-Little Kings" descended from a connubial union between Jesus Christ and Mary Magdalene.
This is a point when tour groups typically want to know how much of Brown's book the tour guide takes for true and how much is pure fiction. But our guide, Brad Newfield, thinks such debates spoil the spell of the book and the tour.
The Louvre is the chief destination of this particular tour. The murder of the curator that opens the book takes place in the Louvre.
Of course, the Louvre and many of its works are centerpieces of the book.