It took ten years to raise the film 's $ 13,000,000 budget . In addition to the theatrical version , the filmmakers have prepared a longer version to be released on television as a mini-series . Filming began in April 2011 , with support from backers in Austria , Poland and Italy , with RAI supporting with 5.8 million euro , and another million euro from the Friuli region . The title 's allusion to the September 11 attacks is intentional . Director Martinelli explained that while that date is associated with the attacks on the United States , few people know that the date also marks the historical events of 1683 when 300,000 soldiers moved from Constantinople to Vienna with an intent to capture Rome and turn St. Peter 's Basilica into a mosque
September 11 attacks
September 11 attacks
The Day of the Siege: September Eleven 1683