Museum director Alessandro Vezzosi gave an opening statement
The "trial" is being held in Vinci, Italy, and an opening statement was made by Alessandro Vezzosi, director of a Leonardo Da Vinci museum, on Friday.
"Leonardo is misrepresented and belittled," he said beforehand.
No-one will represent the book but many fans are expected to attend the event in Leonardo Da Vinci's hometown.
Many readers assume the story, linking Da Vinci with a secret society that has held the secret of the Holy Grail for centuries, is completely true.
Author Dan Brown has said: "All of the art, architecture, secret rituals, secret societies, all of that is historical fact."
But the book has sparked heated debate among historians, many of whom have dismissed Mr Brown's version of events and his central claim that Jesus had a child with Mary Magdalene and the Holy Grail is their bloodline.
The "trial" is taking place at the Palazzina Uzielli in Vinci, near Florence. The town's vicar, Monsignor Renato Bellini, said the book gave an inaccurate view of Catholic society Opus Dei.
"This book depicts the movement as a mysterious centre of political and economic power that tries to hide the historical truth on Jesus and Magdalene, which is absurd," he said.
A representative of Opus Dei would take part in the mock tribunal, he added.
Mr Vezzosi, director of the Museo Ideale Leonardo Da Vinci in the town, said he would produce documents and photographs to prove many of the claims about the legendary artist were false.
"His importance is misunderstood, he was a man full of fantasy, inventions and genius," he said.
As well as the original novel, published in 2003, another 10 books have been written to debunk its claims and a booming tourist industry has sprung up around its sites in France and the UK.
What do you think of the historical claims in the book - did you take them as gospel, or are they pure fiction?
I think that people are far too ready to dismiss a work of fiction that investgates an area of history that has always contained discrepancies. The bible is not an historical document and neither is the DaVinci Code. If people are truly comfortable with their faith they will be able to take on such interpretations as Dan Browns' (and many others) without throwing up a storm, at the end of the day their faith is not based on fact, by its very nature it is the opposite of fact, it is a lack of certainty.
James Bishop, Tunbridge Wells, England
I enjoyed reading the book, despite some flaws in the writing style. But even whilst reading the book I was suprised by the many errors in the story, and after doing some hugely interesting background reading, error upon error in the 'facts' presented itself. They are quite right to put the book on 'trial' for misrepresenting figures like Leonardo da Vinci because as just a first year art history student I could counter many allegations about his works. However, the book is a very good stimulus for people to go deeper behind the meaning of religion but it should not be taken for a true account of religous events.
Henk van Klaveren, Bergen op Zoom, The Netherlands
The claims in the Da Vinci code are just as plausible as the claims in the Bible. No modern christian has actually seen God, or Jesus, in the flesh, and yet they can claim their beliefs as truth. Why should the same not apply to the book? The trouble is, religious zealots are too closed minded to accurately question their own views.
Rob Stone, Stafford, UK
The book is a first rate adventure-mystery. The highly defensive reaction of so many is amusing. The most difficult claim to rebut is that of Mary appearing in the Last Supper. If that is a painting of a man, then Da Vinci was not as good an artist as I believe him to be.
Andy Gaskell, Chorley, UK
On a recent plane journey, my husband and I scanned the books that passengers were reading. A clear third of them were nose deep into a Dan Brown book. Clearly his "historical" claims have grabbed the attention of today's society. No more do people sit down and just take things as the truth when it comes to religious and political issues. Whether the "facts" in the Da Vinci Code are indeed factual or if they truly belong on the fiction list, one thing is certain - it has made a lot of us sit up, pay attention and question what has been handed down to us from the church for hundreds of years. Hoorah to Dan Brown for that.
This is very silly. These ideas have been around for years, in more factual books (The templar revelations, Holy blood & Holy grail etc.), that haven't appeared to the masses! Surely, all this hysteria over a storybook which has reached the masses has scared some societies out there to take action and curb the trend!
It took almost a thousand years after Jesus passed away for the Grail story to appear. What was happening to the knowledge of the Grail during that time and why was such an important section of the life of Christ never referred to before hand. Either the original Grail story is a well-crafted fabrication or the Christian Church is covering something up. The more the Church protests the more I feel they are concerned the truth will be revealed.
Michael Haynes, Stoke on Trent, Britain
The whole point of a novel is to create a scenario whereby the reader is addicted to the story and becomes involved with it as well as enjoy it so much that they "advertise" the book through word of mouth. In order to do so, Dan Brown touched on a taboo subject, exagerating on certain aspects so as to intensify his views and claims thorugh his words.
Dimitri Severis, Nicosia, Cyprus
It's a novel.... what you choose to believe or not believe is a matter for the reader. Are we going to disect every other novel ever written about secret organisations and rituals? Let me go and look up the definition of 'fiction'again. I agree with the sentiments above too - "the claims in the book are just as likely to be true as those in the Bible". There's no proof for that story book either!
Many years are missing in Jesus' life in The Bible stories, who is to say what happened in that time. Brown? the Christian church? Both books tell a story taken from historical fact.
Dave Gorman, Ayrshire, UK
Why did Vatican City and the Vinci city over-react in such fashion? Dan Brown did nothing to defame the great master. All is allowed In the world of creativity. Remember Nikos Kazantzakis's The Last Temptation of Christ, Umberto Eco's The name of the rose or even Passion Of The Christ? They are innovative works of art which all once roused much sensation. Do they still provoke people? Negative. This mock trial only boosts the sales of the book and tourism of France and UK. Reticence and tolerance for sure will silence the noise.
Helen Sim, Hong Kong, China
A large population of the world believes in the (arguably) fictitious stories of the Bible. So why is it so hard for us to allow readers to buy into these stories? In my opinion, the claims made by Brown have just as much credibility, if not more, than most of the stories in the Bible.
Liona Venturini, Philadelphia, PA, USA
The book is a series of cliff-hangers that keeps the reader interested and wanting to go on. The writing is sometimes a bit clumsy and it is about 300 pages too long, and gets annoying nearer to the end. Overall a good read but I don't think it deserves the hype it gets. The church should have shut up and most of us would never have read it or heard about it. Very similar to the Passion of the Christ in that it has achieved a greater audience due to its critics being so vocal.
Andrew Lee, Edinburgh, Scotland
The book was hugely enjoyable. As far as I can see, the claims in the book are just as likely to be true as those in the Bible.
Jane, Essex, England
While many of the claims and facts are forced or stretched, there are many kernels of truth in the story. I do believe that Jesus was married to Magdalane and that they had children. Many of the claims are touching truths, but are often bent to suit the story. The information in the book is not new and has been bubbling underground for thousands of years.
Richard Kennedy, New York, USA
Interesting novel - bizarre and pointless worldwide reaction... I'm just waiting for the headline Novelist Accused of Writing Fiction.
Roy Sharp, Manchester
Er... Dan Brown is in the business of selling books... as many as he can. I think we can be pretty sure of his motives.
John Cahill, London, UK
The Da Vinci Code is false. There is nothing true to historical fact in it. It is another attempt to destroy, by lies, a formal religion.
Lynn, Tell City, USA
I enjoyed reading the novel as a work of fiction based around some historical fact and ideas. However, the debate that I think is more worthwhile discussing rather than Da Vinci's role in the Holy Grail is the concept of Jesus' relationship with Mary Magdalene. He may be considered the Son of God, but he was still a man.
Roddy Fraser, London, UK
As one who has grown up surrounded by theology and art history, it was an entertaining piece of fiction pulling interesting facts and images from reality, but it is just that - an entertaining piece of fiction.
Erin, Ottawa, Canada
If so many people believe it to be true, then how can it be fiction?
Steven Stone, Sheffield
I really enjoyed the book mainly because of the connection between one of the greatest painter and the Holy Bible. I am a Christian but still have some questions about the Bible and the book gave me an open mind about a new direction on how Christianity could have been written? Meanwhile, I do not denied that most of the book were pure fiction and it is to the individual to decide what it wants to believe.
Nicole Gaskin, London
An American rewriting history. Deja vu!
Dan Pryce, Canada
Don't care either way - the best book I have read, not only for an exciting plot but for provoking the desire to find out more about the fascinating locations and issues covered. The willing suspension of disbelief came easily for me!
Hilary Wood, Portsmouth and Southsea, England
America is the breeding ground for these kinds of theories. Most of us take them with a great grain of salt and move on.
Al Hough, Murray, KY USA
The facts speak for themselves, as the saying goes, there's no smoke without fire.
Spencer Paynter, Dudley West Midlands UK
Remember the day Orson Welles' Martians landed in Grovers Mill, New Jersey? The Da Vinci Code falls in the same category - believable, but not to be believed.
Hanna, Kranskop, SA
I would like the facts in the book to be true and at first reading believed them, but after finding out more I am not too sure. It is a good story though, even if not wholly accurate!
Nicola Fielding, Edinburgh, Scotland
I'm starting to feel quite outnumbered, but I for one have found many of the facts from Brown's book even more credible after reading some of the rebuttal books. Most of the evidence on either side seems circumstantial, and I lean toward Brown's assessment of the church as historically biased against women, one American atheist's opinion.
Matty Schwartz, Brooklyn, NY, USA