The July 2, 2011, service will take place in the Palace's Court of Honor. In another new – and uncharacteristic – gesture, palace gates will be left open and giant TV monitors set up to allow some 4,000 people to view the wedding service when it is held in the Place du Palais.
The "religious ceremony will be held at 5 p.m. in the courtyard where we have the long staircase," a palace spokesperson tells PEOPLE. "It will be an open-air event."
A source added, "Whether these 4,000 will be invited guests or [members of the] public is still being discussed."
Monsignor Bernard Barsi, Archbishop of Monaco, will conduct the religious ceremony and Mass. Plans also call for the wedding to be telecast live internationally, just as was the April 1956 religious ceremony of Albert's parents, the screen star Grace Kelly and Prince Rainier – a pioneering event in its day.
Prince Albert and Wittstock's civil service, which is required by law, will be held the day before the religious service, on Friday, July 1, in the Palace Throne Room. Presiding at this ceremony, which is expected to involve no more than 100 family members, relatives and friends, will be the Principality's royal registrar Phillipe Narmino.
Earlier this year, Prince Albert jokingly announced that he had "officially" forbade it to rain on his wedding day.
As for who will design the bridal gown, sources say Wittstock is deciding between Christian Dior and Giorgio Armani.