Queen Christina of Sweden caused a scandal when she stepped down from the throne and converted from the state religion of Lutheranism to Catholicism in 1654.
Known for her unconventional dress sense, deep voice and masculine behaviour, she is believed to have been born with a mix of female and male genitals and hormones.
An intense relationship with one of her ladies-in-waiting, with whom she sometimes shared a bed, fuelled rumours that the queen was a lesbian.
An eight-page parchment document that announced her abdication, complete with seals from members of the Swedish parliament, will be part of the exhibition of 100 documents in Rome's Capitoline Museums.
The Vatican Secret Archives contain one of the world's richest collections of historical documents, spanning more than 1,000 years, from the 8th century until modern times.
Few of the leather-bound documents, which are packed into more than 50 miles of shelves and in climate-controlled chambers, have ever left the walls of the city state.
The exhibition, called Lux in Arcana, includes letters and treaties relating to Henry VIII's request in 1530 for his marriage to Catherine of Aragon to be annulled, the heresy trial of Galileo, the astronomer, and the 14th century trials of the Knights Templar.
The collection also features the papal order which excommunicated Martin Luther in 1520 and a letter written by Mary Queen of Scots, a few weeks before her execution, to Pope Sixtus V.
After her conversion to the Catholic faith and renunciation of the Swedish throne, Christina moved to Rome, where she was triumphantly received by the Church.
She initially stayed in the Tower of Winds, a frescoed tower inside the Vatican Secret Archives, but later moved into Palazzo Farnese, which is now the French embassy.
She had a French marquis murdered in her presence after he betrayed her plans to become Queen of Naples.
She died in 1689 and is one of the few women to be buried in St Peter's Basilica.
Scientists exhumed her body in 1965 to search for skeletal evidence that she was a hermaphrodite but the results were inconclusive.
Even so, she became a symbol of lesbianism and cross-dressing in the 20th century and inspired plays and musicals.
The Secret Archives exhibition, which commemorates the 400th anniversary of the establishment of the archives in their present location, runs until Sept 9.
Few of the leather-bound documents, which are packed into more than 50 miles of shelves and in climate-controlled chambers, have ever left the walls of the city state.
The exhibition, called Lux in Arcana, includes letters and treaties relating to Henry VIII's request in 1530 for his marriage to Catherine of Aragon to be annulled, the heresy trial of Galileo, the astronomer, and the 14th century trials of the Knights Templar.
The collection also features the papal order which excommunicated Martin Luther in 1520 and a letter written by Mary Queen of Scots, a few weeks before her execution, to Pope Sixtus V.
After her conversion to the Catholic faith and renunciation of the Swedish throne, Christina moved to Rome, where she was triumphantly received by the Church.
She initially stayed in the Tower of Winds, a frescoed tower inside the Vatican Secret Archives, but later moved into Palazzo Farnese, which is now the French embassy.
She had a French marquis murdered in her presence after he betrayed her plans to become Queen of Naples.
She died in 1689 and is one of the few women to be buried in St Peter's Basilica.
Scientists exhumed her body in 1965 to search for skeletal evidence that she was a hermaphrodite but the results were inconclusive.
Even so, she became a symbol of lesbianism and cross-dressing in the 20th century and inspired plays and musicals.
The Secret Archives exhibition, which commemorates the 400th anniversary of the establishment of the archives in their present location, runs until Sept 9.