True

Paris had its own version of the Greenwich Meridian. The Paris Meridian–the French version of zero longitude– was first plotted in 1718 and recalculated in the early 1800s. It predates the Greenwich Meridian. And yes, it does bisect both the Louvre and the church of Saint-Sulpice.

The Paris Meridian is marked with brass disks. Dutchman Jan Dibbets laid down the disks–135 of them–in 1994 as an art installation.

The Louvre pyramid was commissioned by the French president himself. Francois Mitterrand asked architect I.M. Pei to execute the commission–and the result, as Dan Brown says, was certainly controversial.

The Church of Saint-Sulpice has a polished strip of brass set in its floor. It's an astronomical gnomon that works like a sundial. And yes, it does climb a stone obelisk on the church's north-south axis.

Sir Leigh Teabing's estate, Chateau Villette, really exists. However, it's not as close to Versailles as Brown says. And Teabing doesn't actually live there.

False

There are 666 panes in the pyramid at the Louvre. Not exactly. For one thing, 666 isn't divisible by four. The official answer is 698.

It would take a visitor an estimated five weeks to "properly appreciate the 65,300 pieces of art in the Louvre." For Secrets of the Code, David A. Shugarts calculated that if you spent one minute in front of each piece of art, it would take 45 days at 24 hours a day just to visit all the artwork, never mind appreciate it.

The caretaker of Saint-Sulpice is a nun who lives in a two-room apartment upstairs. Umm, no.

A temple of Isis lies beneath the sanctuary. No, but the crypt does contain Romanesque walls and columns.

Sophie Neveu's SmartCar gets "a hundred kilometers to the liter." Sadly (this would be one way to ease the gas crisis), SmartCars, which are just 8 feet long, guzzle fuel at five times that rate.