The terraforming plant kaluthin created by Darth Rivan grew all over Almas except for a wide area around the fortress, creating a large desert with the fortress as a focal point. It was a very strong focal point for the dark side.
The castle was plagued with mechanical traps which could not be detected with the Force or with advanced technological means. He would use Mandalorian iron, resistant to the Force and to lightsabers, to keep his most valued books, and for the floor of his lightsaber training room. He also designed the fortress so that his slaves/prisoners (which included at least one Jedi) would be unplugged from the Force, feeling absolutely lost and despairing. Darth Rivan wrote his autobiography in Sithese in the inner walls of his fortress. Rivan also kept the enslaved ghost of his apprentice Darsin in the crypt, with the eternal order of protecting the fortress.
The Almas Sith fortress
The tower was once part of a larger dome-like structure from which Rivan aimed to perform research on the Sith battlelords. It did not have an apparent door, leading experts to believe either that it had a hidden one, probably underground, or that Rivan had some power to go through walls.
However, during the New Sith Wars, the Jedi found Rivan and expelled him from the planet in the Battle of Almas. The structure was destroyed, but the inner tower, later known as the Almas Sith Fortress, proved impervious to blaster fire. Nevertheless, the Jedi left the planet, caring little about the empty fortress. Rivan's fortress and the planet itself were forgotten.
After the Battle of Almas, the Cularin system was forgotten and the fortress laid abandoned for centuries until its rediscovery in 232 BBY. During her initial scouting, Reidi Artom noticed the fortress, but found it too creepy to approach it. She also noticed kaluthin still in the fortress area. She decided that this was more a Jedi affair that hers.
In 188 BBY, Jedi Master Qornah and his Padawan learner Kibh Jeen came to the fortress to research it. Influenced by the dark-side site, Jeen fell to the dark side, killed Qornah and began the Dark Jedi Conflict. Seven years later, Jeen was defeated by the Jedi, and the Almas Academy was built in the opposite face of Almas, to watch over the Sith fortress. Academy founder Nerra Ziveri, convinced that the fortress would be very important in the future of the galaxy, spent time attempting to probe its mysteries.
Jedi comparing the dark-side taint in the Fortress with the presumed dark-side site known as Kaernor's Smile, in the same planetary system, always concluded that the Smile was not a dark-side site while the Fortress was. Any visitor felt "something strange" from more than miles from the Fortress (the wasteland was bigger than that distance), and anyone without training in the Force was commonly unable to resist it.
In the last years of the Old Republic, a group of dark-side cultists calling themselves the Believers found subterranean entrances to the Fortress and used it as their base of operations for a time before being discovered by the Jedi.
Shortly after the Invasion of Naboo, criminal Len Markus found the Sith artifact Darkstaff, which had been both possessed and feared by Darth Rivan. Markus tried to leave the Cularin system in a ship but, when nearing the orbit of Almas, his ship was shot by a Force lightning from the Almas Sith Fortress. As a result of this, the Darkstaff was damaged, Markus was presumed dead and the Cularin system disappeared for one decade, before reappearing just as suddenly.
Soon afterward, the Jedi Order took control of the Almas Sith Fortress. The Almas Academy, in the other hemisphere of the planet, sent a team of Jedi both as research team and as guards against a possible attack from the Believers. The Jedi had not explored the whole fortress, as they had not discovered all the traps or the dark-side taints it could have. Some twenty Jedi were there at any time.
During the beginning of the Clone Wars, the Fortress was invaded by a team sent by Markus. These raiders intended to perform a Sith ritual to create battlelords in the crypt of the fortress, and at the same time repairing the damaged Darkstaff. In the process, they killed four Jedi guards and captured two others. They performed the ritual, but it was ineffective—instead of creating Battlelords, it absorbed the Force essence of the victims. The raiders left, leaving behind the bodies of the casualties.
The raiders left three of the Jedi corpses in their guard post, but took the fourth one and used it as a bait for an ambush with gundarks, to cover their tracks killing any search team the Jedi could send. As the raiders performed their act during a sandstorm, most of the proofs were destroyed. However, Jedi illusionist Treibeiu, who was assigned to the fortress, kept in her memory the crime scene as she had seen it, and could use her powers to reproduce it—showing, for instance, wampa footprints.
The Almas Academy sent at least three search teams to find the missing bodies. Almas Jedi Master Lanius Qel-Bertuk refused to send Jedi-only teams because the attack could have been thought to bait the most powerful Jedi in the Academy. The search was fruitful: At least two of the three missing Jedi were found, plus the bodies of the intended Battlelords, and proofs suggesting that the leader of the raid was slaver Phylus Mon.
During the years following the Yuuzhan Vong War, members of the New Jedi Order were prohibited from venturing near to the fortress.
- Living Force Campaign Guide
- Jedi vs. Sith: The Essential Guide to the Force
- The Complete Star Wars Encyclopedia
- The Clone Wars Campaign Guide
- Star Wars: The Card Game — Darkness and Light