Experts in the show include Oxford Professor Karen Ralls, religion history author Timothy Freke, and Richard Leigh, the co-author of "Holy Blood, Holy Grail", the 1982 book upon which "The Da Vinci Code" based much of its history. The program was shot in places like Rosslin Chapel in Scotland, the London Temple (built by the Templar Knights), various cities in Southern France, and at the Louvre Pyramid, all of which are featured in the book. The program is also the first widescreen, high-definition program produced for The History Channel. It premiered 16 January 2005 at 8 pm pst., and aired again 17 January 2005 at 6 pm.