 At the climax of the novel, the protagonist follows the line of Arago medallions to the Louvre museum, where (according to the book) the Paris Meridian passes beneath the so-called the "Inverted Pyramid" in an underground mall in front of the museum.Following the tradition of esoteric interpretations of this meridian, the novel hints that this is the final resting place of the Holy Grail.The fact that the meridian passes near the "Inverted Pyramid" is also noted in "Le guide du Paris maçonnique" ("Guide to Masonic Paris") by Raphäel Aurillac, who likewise ascribes some deeper, esoteric significance to this.