Stonehenge is presented as an ancient sanctuary and observatory, but in the novel it also becomes the climactic destination of an imagined Templar plan. Colonel Ardenti places it at the end of a route through sacred sites, where the Templars’ descendants are supposed to unlock the power of the Holy Grail; later, the same monument is folded into an elaborate theory of telluric currents and planetary correspondences. Its narrative importance lies in this double life: a real place whose accumulated associations make it seem to confirm a history that the characters themselves are constructing.

The final station in Ardenti’s plan

In his account of the alleged Templar design, Ardenti names Stonehenge as the last meeting place. He describes it as an ancient Celtic stone sanctuary of the sun, an especially privileged point from which the reunited descendants of the Templars of Provins could survey secrets hidden behind seven seals and discover how to use the immense power of the Holy Grail. England thus supplies the culminating landscape for a story that has already connected Templar survival with an expanding network of sacred locations.

Ardenti gives the itinerary a visual form as well as a destination. Tracing its supposed development from a northern castle through Jerusalem, Agarttha, Chartres, the Mediterranean coast, and finally Stonehenge, he says, produces a rune. He then connects that imagined figure to a second alignment of centers of Templar esotericism, including Amiens, Troyes, Reims, Chartres, Rennes-le-Château, and Mont-Saint-Michel, and to the constellation of Virgo. Stonehenge functions here as both endpoint and proof-like landmark: its place at the end of the route makes the invented pattern appear complete.

Belbo’s response to Ardenti’s climactic revelation is dry rather than reverent. His Piedmontese expression of polite amazement conveys an almost fatalistic conviction that Ardenti is irreparably foolish, though Ardenti mistakes the reaction for admiration. The contrast exposes the gap between the colonel’s confidence and the skepticism of his listeners even as his story supplies material that will later feed the Plan.

From a real castle to a constructed secret

Years later, Casaubon’s visit to Tomar changes the way he interprets the message Ardenti had shown them. He decides that the castle named in the message must be the Castle of the Ordonation at Tomar, rather than the legendary Monsalvat or Avalon. In his reconstruction, the Templars could have met there under the protection and freedom enjoyed by the Knights of Christ. He leaves Portugal convinced that the Templars had devised a six-hundred-year plan beginning at Tomar and ending in their own century, and he proposes to reconsider the sequence of the other meeting places, including those Ardenti had named.

The change is not the discovery of independent evidence for the secret. Casaubon explicitly recognizes that the task is not to uncover the Templars’ hidden plan but to construct one. Stonehenge therefore keeps its place in the story less as a verified historical station than as a powerful point in a chain whose connections can be revised whenever a new interpretation seems to fit. The monument’s symbolic force helps make the route persuasive, while the shifting route reveals how much of its coherence comes from the interpreters.

Megalithic observatory in the expanded system

As the Plan grows, the group’s explanations turn Stonehenge into part of a supposed global technology. In one account, menhirs are imagined as sensitive devices placed where telluric currents branch or change direction, while lines mark the routes of those currents and dolmens serve as chambers in which energy accumulates. Stonehenge, along with other stone circles, becomes a microcosmic and macrocosmic observatory: its builders are said to have studied the stars in order to infer the hidden pattern of earthly currents, according to the principle that what is above corresponds to what is below.

The theory does not stop at prehistoric monuments. The Eiffel Tower is reimagined as a metal menhir and celestial antenna, collecting signals from the planet’s supposed underground valves and comparing them with signals from the sky. The history of science and even satellites that photograph the Earth’s crust are then absorbed into the same interpretive network, as if modern instruments were continuing the work attributed to Stonehenge. The shift makes the monument less an isolated wonder than a template: once the characters treat it as an instrument for reading the world, almost any later structure or technology can be assigned a place in the same system.

Narrative significance

Stonehenge’s changing role illustrates the Plan’s method of turning resemblance into evidence. Ardenti makes the monument the destination of a secret itinerary; Casaubon later reorders the itinerary around Tomar; and the group’s subsequent cosmology recasts megaliths as stations in a planetary apparatus. Each version preserves the aura of Stonehenge while changing what it supposedly proves.

The result is a deliberate tension between historical place and interpretive projection. Stonehenge’s genuine antiquity and fame give the invented story a compelling endpoint, but the narrative shows how readily that authority can be recruited into a pattern assembled from disparate sites, myths, and technologies. The monument is not the secret’s confirmation so much as the point where the characters’ appetite for a complete design becomes most visible.