In 2006, one of the world's most famous - and sometimes controversial - films was released: the Da Vinci Code, a mystery thriller based on the novel by Dan Brown in which a professor of religious symbology gets involved in an investigation that uncovers secrets buried deep by religious leaders for generations.

Perhaps unsurprisingly the film was met with harsh criticism by the Catholic Church - which did not stop it from reaching commercial success and being followed by two sequels.

What not many could deny, though, was the intricacy of the genius plot. The book is the first instalment of Dan Brown's Robert Langdon series, that consists of three titles so far, and is set to get its fourth part this year.

Beyond the series, Dan Brown has also put out two standalone novels and a children's book. But which of his titles are the most known?

Here is a list of all of Dan Brown's published books, ranked in order of popularity according to their number of readers on book review platform

1,431 ratings

A children's picture book by Dan Brown, Wild Symphony features a musical journey through the animal kingdom, led by Maestro Mouse, who is preparing a concert with his animal friends. Each animal, like a blue whale, cheetah, or swan, has a unique musical portrait and a special secret to share, often with a motivational message for children.

The book was illustrated by Susan Batori, and includes original musical compositions that can be listened to through a free app that uses augmented reality. The author donated all US royalties derived from the book to support music education for children worldwide, through the New Hampshire Charitable foundation.

343,541 ratings

In Origin, Harvard professor of religious symbology Robert Langdon finds himself embroiled in a global event when atheist billionaire Edmond Kirsch announces he has made a revolutionary discovery that will challenge humanity's understanding of its origins.

Kirsch's discovery is met with both excitement and opposition, and Langdon becomes entangled in a race against time to protect the discovery - that could change the relationship between humans and technology - from falling into the wrong hands.

Origin topped the New York Times bestseller list for 23 weeks upon release.

576,227 ratings

Just before Origin, in Inferno, Robert Langdon wakes up in a Florence hospital with amnesia and a mysterious object. He is pursued by a female assassin and must decipher codes related to Dante's "Inferno" to stop a scientist's plan to trigger a global catastrophe.

Working with Dr. Sienna Brooks, Langdon races against time, exploring historical sites and art to unravel the scientist's motives and prevent the potential end of the world.

A film adaptation was released in 2016, to mixed reviews.

634,472 ratings

This time, in The Lost Symbol, Langdon is drawn into a mystery surrounding the kidnapping of his mentor, Peter Solomon, a prominent Mason. Langdon must decipher a series of coded symbols and navigate a world of Freemasonry to save Solomon and uncover a chilling global conspiracy.

The story unfolds in Washington D.C., with Langdon and his allies pursuing a trail of hidden secrets and ancient mysteries, ultimately leading them to the core of a dangerous plot.

The book sold one million in hardcover and e-book versions in the U.S., the UK and Canada on its first day of release, making it the fastest selling adult novel in history.

654,246 ratings

NSA cryptographer Susan Fletcher discovers that an NSA code-breaking machine has been compromised by a mysterious, unbreakable code. This code, created by a disgruntled former employee, Ensei Tankado, threatens to cripple U.S. intelligence if released.

Susan, along with her fiancé David Becker, and others, must race against time to understand and destroy the code, facing betrayal and danger as they delve deeper into a complex web of government secrets and hidden motives.

The novel explores the ethics of government surveillance of electronically stored information - a topic it was criticised for allegedly not being well-informed about, by some readers.

688,083 ratings

In Deception Point, intelligence analyst Rachel Sexton uncovers a plot involving a fake meteorite discovery, initially presented as proof of extraterrestrial life, which could influence a presidential election - in which her father is a candidate.

As she and oceanographer Michael Tolland investigate, they are pursued by a deadly task force attempting to silence them, forcing them to flee. All before the truth reveals a larger deception, pushing them to expose the conspiracy before it's too late.

2,454,606 ratings

Brown's second most popular novel centers around Langdon and cryptologist Sophie Neveu, who are drawn into a murder mystery at the Louvre Museum. This investigation leads them to uncover a hidden secret society, the Priory of Sion, and a conspiracy involving the Holy Grail, the Vatican, and the true identity of Jesus and Mary Magdalene - which had been hidden by the Church for centuries.

The Da Vinci Code provoked a popular interest in the concept of the Holy Grail at the time, and was extensively criticised by many Christians, who considered it to be an attack on the Catholic Church. It was also subject to scrutiny by scholars, who pointed out historical and scientific inaccuracies.

Despite controversies, it became a massive worldwide bestseller, and inspiring a film adaptation starring Tom Hanks.

3,320,689 ratings

In Brown's first Robert Langdon instalment, - and his most famous novel - the title character teams up with scientist Vittoria Vetra to race against time to save the Vatican from an impending disaster, as The Illuminati, a secret society, threatens to destroy the city with a powerful antimatter bomb while kidnapping four cardinals during a conclave.

Langdon and Vetra must decipher ancient symbols left by a member of the Illuminati, following the "Path of Illumination" to find the antimatter and free the cardinals.

The book, despite coming before The Da Vinci's Code, was adapted into the first film's sequel, in 2009. The movie was received with mixed reviews, but was critically considered better than its predecessor.