The crypt , that is situated inside the church and that cointains the Royal Graves of the House of Savoia , was realized in the underground of the cathedral by the will of the King Vittorio Amedeo III , despite the wish of having a mausoleum for the deceased of the Royal family was already there at the period of his grandfather , King Vittorio Amedeo II. The project was entrustred to the architect Francesco Martinez in 1774 , Filippo Juvarra's grandchild , who concluded it in 1778.