After centuries of being kept under lock and key, the Vatican has started opening its Secret Archives to outsiders in a bid to dispel the myths and mystique created by works of fiction such as Dan Brown's Angels and Demons. The archives, until now jealously guarded from prying eyes, provide one of the key settings in Brown's thriller, in which Harvard "symbologist" Robert Langdon, played in the 2009 film by Tom Hanks, races against time to stop a secret religious order, the Illuminati, from destroying Vatican City.
In the movie, the Secret Archives are portrayed as a hi-tech cross between the Pentagon and the lair of a James Bond baddy, complete with bullet proof glass and swish steel elevators.
In reality, the archives rely on disarmingly old-fashioned technology, with a creaking metal lift connecting different floors and millions of documents catalogued in 1,300 parchment-bound inventories dating back centuries.
They have been open to carefully vetted academic researchers for more than 100 years, but in the last few months the Vatican has granted tours to select groups of journalists and members of the public, allowing a glimpse into one of its inner most sanctums.
The Daily Telegraph was invited on the most recent tour this week, along with about 25 enthusiasts from around the world who earned their places by buying a recently published, lavishly illustrated book on the archives.
The archives are housed in a fortress-like wing of the Vatican behind St Peter's Basilica, with the avenue leading to the building watched over by a phalanx of Swiss Guards in ceremonial uniform and officers from the city state's own police force, the Gendarmerie.
The two-hour visit revealed more than 52 miles of shelving in an underground, concrete- walled bunker, as well as exquisite 16th century wooden cabinets packed with priceless parchment letters sent by princes, potentates, heretics and heathens to the Holy See.
They include correspondence between the Vatican and some of the most prominent figures in history, including Erasmus, Charlemagne, Michelangelo, Queen Elizabeth I, Mozart, Voltaire and Adolf Hitler.
One of the most elaborate is a letter sent by English peers and bishops to Rome in 1530 demanding to know why Pope Clement VII was taking so long to annul the marriage of Henry VIII and Catherine of Aragon. It bears 83 signatures, below which dangle 81 official seals on red cord.
The oldest document in the archives dates back to the 8th century, while others relate to the trials of the Knights Templar from 1308-1310 and the enrolment of the first contingent of the Swiss Guard in 1505.
The archives' custodians are at pains to dispel the conspiracy theories and aura of intrigue fostered by Brown's hugely popular page-turners.
"The word 'secret' is not quite right – it comes from the Latin 'secretum' which in fact translates more accurately as 'private'. These documents are the private archives of the popes. We really don't have many secrets," insisted Marco Grilli, the secretary to the prefecture of the archives.
When pressed, however, he admitted that there is a section which really is secret and that remains off-limits to historians and academics.
It contains papers relating to the personal affairs of cardinals from 1922 onwards, as well as centuries of annulment of marriages. Whether there are any bombshells lurking in these confidential files is a matter known only to the Vatican.
Nor do scholars have access to any papal papers from after 1939 – the beginning of the papacy of the controversial wartime pontiff Pius XII, who has been accused of turning a blind eye to the Nazis' extermination of the Jews.
While the recent scandals over clerical sex abuse have only confirmed the Vatican's centuries-old bunker mentality, the Secret Archives seem to be forging a different approach.
"We were amazed by the access we were given and the speed with which the whole project was completed," said Paul Van den Heuvel, of VdH Books, the Belgian firm which published the glossy volume of high-quality reproductions of 105 documents.
"The Vatican is beginning to realise what an incredible asset it has."