How much of the book 'angels and demons' comes from fact?

"Angels and Demons," written by Dan Brown, blends fiction with historical and scientific elements. While the novel incorporates real locations, artwork, and elements of the Catholic Church, many aspects, such as the secret society of the Illuminati and the specific plot events, are fictional. Brown's meticulous research adds a layer of authenticity, but readers should distinguish between fact and creative narrative in the story. Overall, the book presents a fictional thriller inspired by real-world references.