In Casaubon’s late-night wanderings, Beaubourg becomes more than a conspicuous modern building: he recasts it as a global transmitter and receiver, a gate to the underground kingdom of Agarttha, and a monument to the hidden order he believes has shaped history. Its daytime familiarity only sharpens the terror of this private vision, in which a public landmark seems to announce a secret that almost no one can see.

The Building and Its Imagined Function

Casaubon first recognizes Beaubourg in the Conservatoire’s glassworks section, where an enormous, perforated machine stands taller than he is. Its sign identifies it as a radio apparatus. He instead reads its air ducts and openings as evidence that it belongs to the network of signals and devices he has been assembling in his mind: France, Tunisia, and Russia become points in a scheme involving the Templars of Provins, the Paulicians, and the Assassins of Fez. The geographical contradictions do not weaken his interpretation; he dismisses them as irrelevant to what he calls Transcendent Time.

In his imagined sequence, the Conservatoire is a laboratory and the Eiffel Tower a probe, while Beaubourg is the system’s transmitter and receiver. He pictures the structure at the center of Lutetia as an enormous box fitted with vents and conduits, an ear open to the sky that catches messages and sends them to the center of the globe before returning information from below. Its public function as a place visited by students and listeners wearing Japanese headsets becomes, in this reading, a cover for a machinery whose true purpose is hidden in plain sight.

Beaubourg as a Gate to the Plan

Casaubon identifies the building as a gate to Agarttha and a monument of the Resurgentes Equites Synarchici. He imagines the hidden group’s supporters moving toward their goal through six centuries while billions of ordinary people remain unaware of the Plan, or force themselves not to notice it. The contrast between the building’s visibility and the supposed secrecy of its purpose gives Beaubourg its particular force in his suspicions: it is not concealed but overlooked, available for everyone to see and, in his view, understood by almost no one.

The vision recurs when Casaubon passes Beaubourg after Belbo’s apparent death. The plaza that had been a crowded fairground during the day is nearly deserted at night, with silent groups and a few lights from the brasseries opposite. He sees the building’s air ducts as absorbing energy from the earth and speculates that daytime crowds supply vibrations—or even that the supposed hermetic machine feeds on fresh meat. The change from public bustle to nocturnal emptiness does not calm him; it turns the familiar site into fresh apparent confirmation of his theory.

A Landmark Recast by Paranoia

Beaubourg is part of a larger pattern in which Casaubon connects Parisian buildings, occult imagery, and modern technology. In his account, its relation to the Conservatoire and the Eiffel Tower gives the city a hidden infrastructure, while its enormous ducts make the architectural object appear to breathe, absorb, and transmit. The ordinary explanation remains visible—the sign calls the machine a radio apparatus, and people visit the plaza for familiar purposes—but Casaubon’s increasingly unstable interpretation absorbs those facts into the Plan.

The building therefore marks the distance between public evidence and private conviction. Its openness is central to the irony: Casaubon treats the visible structure as proof precisely because its alleged meaning is not recognized by the crowds around it. Beaubourg does not change in these scenes; what changes is the pressure of the scheme imposed upon it, until a modern public landmark becomes, in Casaubon’s eyes, the entrance and operating instrument of a subterranean world.