WASHINGTON (AFP) - A sequel to the blockbuster thriller "The Da Vinci Code" is set to lift the veil on mysterious Freemason symbols carved into the very fabric of the historic streets and buildings of the US capital.
Novelist Dan Brown has set the new adventures of his hero, scholar-adventurer Robert Langdon, right in the heart of Washington, which could reveal some astonishing facts for history buffs.
Brown "had a contact with us but then cut it short. We are all sitting around waiting for his book to come out but nobody knows what he's going to say," Akram Elias, grand master-elect of Washington's Grand Lodge, told AFP.
According to the pre-publicity, the book -- working title "The Solomon Key" -- will feature Langdon hero of the mass-selling "The Da Vinci Code" and who was played by Tom Hanks in the hit film version.
"For the first time, Langdon will find himself embroiled in a mystery on US soil. This new novel explores the hidden history of our nation's capital," Brown wrote in a posting on his official website.
Washington has strong historic roots in Freemasonry -- an old and widespread fraternity which traditionally practised secret rituals.
Despite its reputation for secrecy, the Freemason community is noticeably open in the United States: lodges are advertised in the phone book and their signs are prominently displayed.
The first US president after whom the city is named, George Washington, was a Mason, as were his fellow founding fathers James Madison and Benjamin Franklin, plus James Hoban, the architect of the White House.
The broad steps, stone sphinxes and colonnades of a Masonic temple dominate a corner of 16th Street near the city center -- one of a number of Masonic lodges in the capital -- and just a stone's throw from the White House.
Elias cites theories that the city's streets themselves are laid out in the shape of secret Masonic signs. "It may be a coincidence, but there are indications that are difficult to ignore," he said.
Establishing the nation's capital, George Washington is said to have demanded that it be laid out in a symbolic square.
"It's fascinating. If you take an aerial view of Washington, you cannot but see the perfect square and the compass which are the universal symbols of Freemasonry ... meaning rectitude and equality," he said.
"Was it on purpose? I don't know, but I think it's difficult to ignore those mysterious aspects," he added. "It adds another level of mystery to the city of Washington."
The shape of a square and compass is also formed by drawing a line on the map between two of the city's major landmarks, the Capitol and the Lincoln Memorial, and along the walls of the White House and the Jefferson Memorial.
At the center of these stands the George Washington monument, a vast brick obelisk whose dimensions themselves are symbolic: 555 feet high by 55 wide (170 meters by 17).
The number five is said to refer to the traditional five orders of architecture, which in turn relates to the Freemasons' regard for geometry as a symbol of order, and of "the great geometrician" -- the supreme being.
Inside the Capitol building, the heart of US lawmaking which sits at the dead center of the square city boundaries, lies a cornerstone laid by George Washington himself, dressed in his ceremonial apron, in a Masonic ritual in 1793.
"Here goes Washington heading a ceremony in order to lay the cornerstone of the Capitol, using corn, oil and wine to send a very powerful message to those who will be working in the parliament," Elias said.
"Their mission should be to work in achieving prosperity, peace and happiness for the American people."
Some play down the perceived prominence of Masons and their symbology, for fear of encouraging conspiracy theories which may be harmful to Freemasons.
"Freemasonry has a very important role in the history of the US and the early American republic," said Mark Tabbert, director of collections at the Washington Masonic memorial in nearby Alexandria, Virginia, and author of the book "American Freemasons."
"But that role is not based on any kind of political or religious construct."
Tabbert offers an alternative to claims of Masonic design in Washington's city plan.
"The design of the US capital is based more on neo-classical style, more related to the attempts to create a new republic based on an ancient Roman republican model than anything that related to freemasons," he said.
Codes and secret signs were Brown's stock-in-trade for the staggering success of "The Da Vinci Code" however.
"I'm nervous about it because I don't think he does very good research," Tabbert said of Brown and his new book. "But fiction writers are fiction writers."