Cathedral

Cathedral was the center of the Thinking Machine world of Synchrony, where Omnius, the Computer Evermind, ruled the robotic empire. The Cathedral was called such as it was the holder of the probe that had been launched from Giedi Prime thousands of years earlier, that caused the rebirth of the machine Empire.

The Giedi Prime Probe
When the Machines conquered Giedi Prime before the Butlerian Jihad, one of the first acts of the Omnius entity on that planet was to launch over 500 probes into deep space. This attempt at colonization failed on almost every world where the space probes landed, but one such probe landed on a far world where it began to build a robotic colony city.

At the end of the Battle of Corrin, in a last ditch attempt to save Machine civilization in the face of the final human conquest of their first empire, the final Omnius entity sent into deep space a radio signal in an attempt to save itself. This signal contained all of the necessary codes and information of the Empire, including the entities of Omnius and his AI savant, Erasmus. As the signal degraded across the cosmos and across the galaxies, it was picked up on the far world that come to be known as Synchrony.

Heart of Synchrony
As the Machine empire rebuilt itself, Omnius and Erasmus held in near-reverence the original probe that had been launched from Giedi Prime centuries earlier. They purposefully built the Machine Empire around the probe, and gave the giant multi-thousand storey flow-metal building that it was housed in, the near-religious name of Cathedral. The probe was enclosed in a giant, four-storey museum-like glass encasement that rotated for all machines to view. It was in the Cathedral that Erasmus spent most of his time in, conducting experiments on, and directing his Enhanced Face Dancer and Augmented human minions.

When the Cathedral was approached from space the high needle-like copper spire of the building could be seen from miles up in the atmosphere. It was to this building that Erasmus had pre-programmed into each Enhanced Face Dancer the ability to "come back" to like a type of homing beacon.

On the Day of Kralizec
As the great day at the end of the age occurred, Kralizec, much of it happened in the heart of Synchrony, in the Cathedral. When the No-ship the Ithaca was captured and brought down to Synchrony, the first group of prisoners was brought to the Cathedral. At this time, it was thought that the ghola of Paul Atreides that had been created on the ship years earlier, could be the Ultimate Kwisatz Haderach. As Omnius already had a clone of Paul, whom he named Paolo, who also could have been the super-being; the Machine leader decided that the two would duel to-the-death.

Paul ended up near death from a mortal stab wound from Paolo; who ended up in an irreversible trance from overdosing on the super-potent version of melange, called Ultraspice. As Paul came back from the brink of death, he declared through Prescience that the ultimate Kwisatz was Duncan Idaho. At the same time, the Oracle of Time appeared in Cathedral, and banished Omnius to another universe permanently.

Later that day in Cathedral, Khrone, machine-appointed leader of the Enhanced Dancers announced that the Dancers were betraying the Machines, and would be assuming the ascendancy of the universe. Erasmus started up the tachyon net, and activated the "kill switch" at the base of the skull of each and every Enhanced Face Dancers in the Known Universe. Soon afterwards, after merging and giving the codes to Cathedral, Synchrony, and the entire Machine Empire; to Duncan Idaho, Erasmus died in the chambers of Cathedral.

Afterwards
Later, the Cathedral remained a part of the harmonious universe that existed between machines and man. As Synchrony became a training center for the Bene Gesserit, the restoration of the Tleilaxu civilization; it is strongly believed that Cathedral remained in Machine hands.