Visiting the cultural jewel to promote his latest book 'Inferno' - inspired by the city's most famous son, mediaeval poet Dante Alighieri - Brown is due to speak at a conference on the subject of mankind's "need for mystery".
Tour guides are already proposing "Dan Brown Tours" and hotels are offering "Dan Brown Packages" less than a month after the book's worldwide release - in a city that is feeling the impact of Europe's economic crisis on tourism.
"There's definitely interest. I've already had questions from various tourists. A lot of people have read the book," said Elisabetta Franchetti, a guide with ArtViva walking tours, which launched its Brown-inspired route on Thursday.
The three-hour itinerary winds its way through the centre of Florence, tracking a gripping chase involving Harvard professor Robert Langdon as he seeks to prevent an act of bio-terrorism that takes up most of the 'Inferno'.
Franchetti said the novel could be a way for mass-market tourists to access Florence's priceless cultural heritage more readily, particularly the lesser-known nooks and crannies that serve as the backdrop to the plot.
The book has already sold nine million copies in 13 countries. Brown's 'Da Vinci Code' sold a total of 81 million copies worldwide.
Franchetti led a tour group across the Ponte Vecchio spanning the Arno River - along the Vasari Corridor used by Langdon in the book to elude his enemies.
"The idea is to enrich everything, to allow people who do not know Florence, who do not know who Dante was, who Boccaccio was, who Petrarch was, who Machiavelli was, to go deeper, be more curious," Franchetti said.
There is no shortage of tourists in Florence, although city authorities complain that visitors are often only daytrippers and want to encourage them to stay for longer to gain a deeper understanding of what the city has to offer.
The number of Italian overnight tourists to Florence fell by around five percent last year, while foreigners were down 0.9 percent with sharper drops for those coming from other European countries, according to official data.
Eugenio Giani, president of the Italian Dante Society and head of the city council in Florence, said he hoped the novel would also inspire more young people to appreciate Dante Alighieri (1265-1321), author of the Divine Comedy.
The famous three-parter is made up of Inferno, Purgatorio and Paradiso.
"The book is important because it renews an interest in Dante, even in Italy," said Giani, speaking in a room in the Palazzo Vecchio where Langdon again escapes his pursuers through a secret door behind a map of Armenia.
"Dan Brown is contributing a lot to this renewed interest," he said.
Giani gave as an example his 14-year-old son who is reading the book and has been asking his father about some landmarks and artifacts mentioned in the book like the Dante mask kept in the Palazzo Vecchio, the seat of the city council.
The city official and Dante fanatic said the book also helped Florence because it placed Dante at the heart of the city from which he was famously exiled.
Giani said he had met with Brown and suggested he visit again "once this hubbub is over" to find new themes for his new novel.
"There is no shortage of secrets here," he told AFP.