- "It's so peaceful here… the Force permeates everything."
- ―Nomi Sunrider
Ossus, known as Idux while under the control of Xim's empire, was the third planet in the Adega system in the Auril sector. Known to the galaxy since before 25,000 BBY, when the Jedi expanded there from the planet Tython and established a Jedi Academy, Ossus would become a popular world of the Galactic Republic. This world would also become a place of great importance to the Jedi, as the site where they stored the sum of their knowledge, though such attentions came at a price. When the Jedi Knight Exar Kun turned to the dark side and became the Dark Lord of the Sith, catapulting the galaxy into the Great Sith War, he attacked Ossus, desiring Sith secrets hidden by the Jedi. During the events this action incited, the Cron Cluster was detonated, spreading a shockwave around the galaxy. Originally a rich, lush world, Ossus was ravaged into an arid and toxic planet when the wave struck the planet.
Certain individuals survived the blast, including several Jedi. Over the passing generations, these people would become more feral, forgetting their heritage and the Force while regarding their abilities from it as magical. They became the Ysanna, Ossus's only native sentience. They, along with the planet, lived in peace with the rest of the galaxy through the Clone Wars between the Republic and Confederacy of Independent Systems, when Ossus primarily became a planet of archaeological importance to the Jedi. Once the Galactic Empire rose to replace the Republic, such studies into the past of the Jedi were halted, however.
After the eventual fall of that government as well, and the rise of the New Republic, Ossus saw major use during a time of war, for the first time since the Sith War of 3996 BBY, during the Yuuzhan Vong War of 25 ABY. It was studied by the Yuuzhan Vong, extra-galactic invaders who wished to conquer the galaxy, while they searched for a way to gain the upper hand against their primary enemies, the Jedi and New Republic, who in turn used it as a rally point for assaults against the Vong. Ossus regained its standing with the Jedi, revived as the New Jedi Order, following the war. Jedi Grand Master Luke Skywalker reopened the Academy there and made it the headquarters of their organization, though he later returned that distinction to the Jedi Temple on the galactic capital of Coruscant.
In an attempt to allow the Yuuzhan Vong to redeem themselves a century later, Skywalker's descendant, Kol Skywalker, founded the Ossus Project, an initiative to use Vong terraforming to restore the surface of Ossus. Due to Sith sabotage, the project failed and infected many individuals with organic parasites. The devastating effects the parasites had on people prompted the Fel Empire to call for an end to the project, which the Jedi would not allow. When the Galactic Alliance defended the Vong at the request of the Jedi, the Empire declared war against their loose rival, crippling and defeating them in 130 ABY. The Jedi moved their headquarters to Ossus once again after Coruscant was ceded to the Empire and Sith. However, two days later, the Sith attacked the Ossus Academy, killing half the Jedi inside and beginning the galaxy's third Jedi Purge. The Empire would later level the entire Academy in a barrage of turbolaser fire.
- 1 Description
- 2 History
- 3 Inhabitants
- 4 Locations
- 5 Behind the scenes
- 6 Appearances
- 7 Sources
- 8 Notes and references
- 9 External links
Ossus orbited the two stars of the Adega system, Adega Prime and Adega Besh. Unlike the other five planets in the system, which circled the center of mass of the two binaries, Ossus orbited both its suns in a figure-eight trajectory. Two moons in turn orbited it: Mim, a rocky, low-gravity satellite with no atmosphere, and Nerit, a temperate terrestrial world with high gravity and a population of Neti expatriates.
Ossus was originally a rugged, lush world with two-thirds of its surface covered in water and an abundance of flora and fauna. In 3996 BBY it was transformed with the destruction of the Cron Cluster into a desolate, irradiated desert world. Chemical and electrical storms swept the land, and little life remained on the surface. Over 4,000 years later, the damage done to the planet seemed to have been reversed. In the time of the Galactic Alliance, some portions of the planet were once again lush with vegetation and inhabited by wildlife. Within a century after this, the destruction done to Ossus was fully reversed with the terraforming technology of Yuuzhan Vong Shapers, who caused the planet to once again teem with life.
Before the Cron supernova, Ossus had a population in the hundreds of millions, inhabiting cities across the globe. The principle city was that of Knossa, whose spaceport was the main thoroughfare for arriving and leaving Ossus. The Cron incident destroyed most of the buildings in these cities.
Though a world of peace, Ossus was not a defenseless planet. Scattered ground emplacements protected it from aerial attack. During the various wars with the Sith, Ossus was used as a staging ground for Jedi and Republic forces. The planet also maintained a well-equipped military fleet for defense. Law enforcement consisted of Jedi Guardians who maintained security in the cities.
Flora and fauna
Ossus had been lush with life before the Cron disaster, but after those events, little of it remained. One of the surviving animals was a hardy quadruped species that the locals used as mounts. By 40 ABY, however, plant and animal life burgeoned again. The region around the Jedi Academy was verdant, with small plots of foliage interspersed among stretches of turf making up the Academy's campus, and kingwood trees covering the lower slopes of the nearby mountains. Bambwood was also found on this world.
The forests were also abundant with animal life. Gokobs, a species of friendly hairless rodents that sprayed a stinking cloud when frightened, spent much of their time scavenging off food scraps from the Jedi academy kitchens. Large brightly-colored tree frogs with sticky tongues also inhabited the treetops, and low-flying academy X-wings could find themselves with several frogs stuck to their undersides, a hazard to flight.
The unusual orbit of Ossus caused some to speculate that, like the Corellian system, the Adega system was artificially designed. However, despite the diligent efforts of archaeologists, no such evidence was ever uncovered.
The planet was home to intelligent life for countless generations. Originally known as Idux, it was absorbed into Xim's empire as he expanded his borders from the Kingdom of Cron. At some time before 25,000 BBY, a group of Jedi Knights from Tython established a school of philosophy there where the concepts of the light and dark sides of the Force were laid down. Here, too, the philosophies of the Living and Unifying Force were established.
Around 25,000 BBY, Galactic Republic scouts exploring the newly-discovered Perlemian Trade Route arrived on Ossus, in what was then known as Wild Space. The leader of the Jedi enclave, Master Haune Tiar was invited to tour the Republic, and his return on Ossus were followed by several weeks of debate among the Order. Following these events, the Jedi appointed themselves defenders of the nascent Republic. Ossus was poised to defend the Core Worlds against the forces of the Tion Cluster and Hutt Space, and so the planet became a fortress world protecting the Perlemian. With the Jedi holding back its enemies, the Republic grew apace.
In 11,933 BBY, after witnessing the massacres committed against alien species during the first Pius Dea crusades, the Jedi Order decided to sever all ties with the Republic and retreat to Ossus. The Jedi would remain there for the next eight centuries, until the Caamasi convinced them to act against the Republic and put an end to the Pius Dea rule.
Several millennia after the fall of the Pius Dea sect and the pacification of the Republic, Ossus had quickly become a leading center of knowledge and learning for the Jedi Order. Odan-Urr trained there under the tutelage of Ooroo, and around 5000 BBY, constructed the Great Jedi Library as a grand repository of Jedi knowledge, containing tens of thousands of texts. Pilgrimages to the world from thousands of planets were common, many of them by Jedi seeking enlightenment. Most Jedi traveled to Ossus at some point in their lives. Academics, too, were drawn to the world, seeking knowledge and research contained nowhere else. Due to its importance to the Jedi, many scholars incorrectly concluded that it had been the birthplace of the Order. Notable students of Ossus included Freedon Nadd, Nomi Sunrider, Dace Diath, Shoaneb Culu, Derrica Praji, and Shaela Nuur.
This oasis of knowledge and peace was doomed, however. During the Great Sith War, Exar Kun slew Odan-Urr, stole a Sith holocron, and recruited many Jedi students on Ossus to the dark side, taking them to Yavin 4. Ulic Qel-Droma later joined forces with Exar Kun, and using Sith weaponry from Naga Sadow's ancient battleship, the Corsair, they detonated the stars of the nearby Cron Cluster in 3996 BBY, causing a deadly shock-wave to spread out across space.
The Jedi were forced to hastily evacuate the planet, and it was during the ensuing chaos that Kun returned with Qel-Droma and a team of Massassi warriors, determined to loot the planet of its riches. Qel-Droma's Mandalorian Crusaders dived into the fray too, firing on the ships of the fleeing Jedi. Kun attempted to take a valuable collection of ancient lightsabers, but was stopped by the Neti Jedi Master Ood Bnar. Bnar transformed himself into a tree, trapping the lightsabers underneath his roots and preventing Kun from reaching them.
Ulic, meanwhile, engaged in battle with his brother Cay, who sought to turn him back from the dark side. When Ulic struck down his brother in a fit of rage, Nomi Sunrider, horrified at what he had done, stripped him of the Force, and the Jedi took him prisoner and fled the doomed planet. The shock-wave hit soon afterward, searing Ossus and killing much of its life.
Post-Great Sith War
The planet was not completely scoured of life, however. Some Jedi had found protection in a cave system under the Eocho Mountains. Over time, their descendants forgot their origins, and came to see their Force abilities as a form of magic. As life slowly crept back onto the world, they emerged to become the tribal Ysanna. Ood Bnar survived as well, protected from the full effect of the supernova in his new form. In order to protect ancient lightsabers, Ood used the force to transform into a tree. His roots covered the lightsabers and protected them. The Cron Cluster's destruction into the Cron Drift made hyperspace travel to the world nearly impossible.
Most of the knowledge of the Jedi stored on Ossus was lost forever in the cataclysm. However, much was moved as well, to locations as far spread as Exis Station, the Jedi Archives on Coruscant, and Derem City on Kamino. The Jedi learned from the disaster, and built storehouses in planets across the galaxy to hold their most valuable artifacts. Contingency plans for evacuation were established in case other important Jedi worlds such as Dantooine were attacked.
Sometime after the end of the Galactic War, Ossus became home to a colony of Jedi who had fled the onslaught of the Eternal Empire conquest by Arcann and Vaylin, led by Jedi Master Gnost-Dural. The Jedi on the planet had established a small colony and worked to recover lost knowledge housed in Ossus' temples and library. At one point multiple Jedi, led by Gnost-Dural, attempted to revive Ood Bnar, who was still entranced in a state of deep hibernation after the Cron Supernova. In 3628 BBY, the Sith Empire sent forces under Darth Malora to Ossus in a pre-emptive strike against the Republic. The Republic responded with forces under General Daerunn, and the colony of Jedi was evacuated. However, the conflict resulted in the reawakening of Darth Malgus, who had survived the events following the Battle of Ilum.
Ossus was a popular location for archaeological teams during the time of the Old Republic. The Hanna Institute of Antiquities, Academy of Jedi Archaeology, and University of Agamar all sponsored studies and excavations of the ancient ruins. In 800 BBY, a dig recovered a lightsaber that would eventually belong to Vima-Da-Boda.
Early in the Clone Wars, several Jedi were dispatched to defend Ossus. A Separatist offensive struck, and the planet fell within days of the Battle of Rhen Var. The CIS established a base on the planet, which was later the target of a Republic attack as one of the opening battles of the Outer Rim Sieges.
When the Galactic Empire came into power, its crackdown on Jedi-related activity brought research to a stop. Extremely few projects on Ossus were funded on the Empire's credit, and private organizations who wanted to do research had to avoid incurring its wrath. Ossus' legacy as a forgotten repository of Jedi knowledge served to inspire Jedi Purge survivor Jin-Lo Rayce to name his fledgling group of Force Adepts the Agents of Ossus, keeping the history of the Jedi hidden, rather than lost. Around 10 BBY, Travgen, a Dark Jedi, found Ossus and hid there from the Empire. Establishing himself in an old administrative center, he eventually rose to control several Ysanna tribes, and was still living on Ossus during the New Republic era.
In 10 ABY, Luke Skywalker and Kam Solusar arrived on Ossus in search of Jedi artifacts to aid in rebuilding the Order, guided there by an ancient holocron of Bodo Baas. Searching the ancient ruins, they encountered a pair of Ysanna, Jem, and Rayf, who they sensed were Force-sensitive. The two Jedi were then ambushed by a band of Ysanna, whose primitive Force-enhanced attacks they easily blocked. Knowing from their strength in the Force that they could only be Jedi, the Ysanna welcomed the two men.
This new allegiance was immediately put to the test. The Galactic Empire had tracked Luke and Kam's approach to the planet, and Palpatine's Dark Side Elite Sedriss QL and Vill Goir were dispatched to capture or kill them. The Ysanna and Jedi fought off their soldiers, and Solusar killed Goir. Sedriss took Jem hostage, and backed up against a tree. However, this tree turned out to be the dormant Ood Bnar, who came to life and killed Sedriss, sacrificing himself in the process. Underneath him Luke discovered the ancient cache of lightsabers, which he took to be a sign of the Jedi's return. The Ysanna then revealed to the Jedi the secret location of the Great Jedi Library, which still held some undamaged texts. Before leaving, Kam and Luke asked the Ysanna if any wished to be Jedi candidates; only Jem and Rayf accepted.
In the wake of Palpatine's subsequent attacks on the New Republic with the Galaxy Gun, its leaders sought a new safe haven. Solusar suggested Ossus, believing that Palpatine would not risk destroying such a valuable repository of Jedi knowledge. The Jedi returned to the planet to ask the Ysanna, and encountered the forces of the Empire, sent by Palpatine to seize several Ysanna to clone and use as host bodies. The Jedi arrived too late to stop them from leaving Ossus, but rescued the captured Ysanna later on Vjun. With the destruction of the Galaxy Gun, the New Republic no longer needed a hidden base, and therefore never relocated to the world.
It was not forgotten, however. The New Republic and New Jedi Order began an extensive archaeological survey of the planet, unearthing its ancient ruins and learning more about the Jedi of old. The Obroan Institute for Archaeology, Hanna Institute of Antiquities, and New Republic Archaeological Corps, as well as groups from across the galaxy sponsored excavations on Ossus. Though they learned much of the planet, the scholars did not fully understand its history; for example, the idea that the Krath had been responsible for the original cataclysm was not taken seriously in academia. The Jedi took a particular interest, as Luke Skywalker believed it was necessary to understand the past of the Jedi before attempting to build a new future for them. The Ysanna grew more accepting of the Jedi, and it was expected that in time they would seek out their Jedi heritage again.
Ossus stood outside the invasion corridor of the Yuuzhan Vong, and so avoided the widespread destruction of the Yuuzhan Vong War. However, all official research was brought to a halt by the war. Vong occasionally visited the planet in search of ancient secrets that could help them exterminate the Jedi. The New Republic, too, used Ossus, taking advantage of its proximity to Vong territory to send strike teams into enemy-held sectors.
New Jedi Order
At the close of the Yuuzhan Vong War, the Jedi chose to distance themselves from the Galactic Alliance on Coruscant. With the praxeum at Yavin 4 destroyed, Luke Skywalker chose Ossus as the new home of the Jedi Order, on the suggestion of Kam Solusar. Not all Jedi moved there at first; Solusar, his wife Tionne, Luke, Mara Jade Skywalker, and their son Ben were amongst those who did. The Solusars became the administrators of the Ossus academy. A new Jedi Temple was built on Coruscant, but its use was chiefly formal, to facilitate communication and cooperation with the Galactic Alliance.
During the Dark Nest crisis and subsequent Swarm War, the Order used Ossus as their principle base of operations. In 36 ABY, Luke Skywalker called a meeting of the entire Jedi Order to resolve the crisis he saw facing it. He reconfirmed the Jedi's commitment to the Galactic Alliance and made an ultimatum to those present; they would put their commitment to the Jedi before all else, or they would resign from the Order. He also established himself as Grand Master of the Order in a bid to make the Masters put aside their differences in the face of his apparent power grab.
Galactic Alliance troubles
When Jacen Solo seized control of the Galactic Alliance government in 40 ABY, he knew that the Jedi would oppose his rule. When most of the Jedi Masters left Ossus to attend the funeral of Mara Jade Skywalker on Coruscant, leaving only Kam and Tionne Solusar and a handful of Knights, Jacen seized his chance and sent a Galactic Alliance Guard division to take control of the academy. Led by Major Salle Serpa, the GAG group claimed to be taking these actions for the protection of the Padawans still in the academy, though their true purpose was to hold the Padawans hostage and prevent Jedi opposition to Jacen.
Shortly thereafter, the Dark Jedi Alema Rar came to Ossus in search of records that would help her understand her new Sith Meditation Sphere. A task force consisting of Jaina Solo, Jagged Fel, and Zekk soon followed her there, only to find Serpa in control of the academy. They, like all the other Jedi there, were forced to play along while the Padawans were still under threat, as Serpa intimated that he would gladly destroy the academy if he felt it was a threat. Alema found the information she sought and left the planet, but her pursuers were forced to remain behind.
Events would change soon, though. Following the assassination of Cal Omas, the Jedi cut their ties to the Galactic Alliance. Jacen Solo, declaring that the Jedi had betrayed them, decided that he needed to take control of the Padawans, and ordered the execution of the Masters and Knights. Serpa rounded up the Padawans in an outdoor courtyard and positioned snipers to take out the Jedi who showed themselves. Several Knights were killed in the conflict, several Padawans were wounded or killed, and Kam and Tionne Solusar were grievously injured, the latter personally by Serpa. Jaina and Jagged were able to avoid the GAG patrols, however, and between them and Zekk, the GAG troops were eliminated and Serpa was captured. The other GAG troopers surrendered, some because they had been opposed to Serpa's actions, others out of fear of the Jedi. After the attack, the Jedi abandoned Ossus and relocated for a time to Endor.
Following the conclusion of the Second Galactic Civil War and the demise of Lumiya's Sith in 41 ABY, the Jedi Order did not immediately return to Ossus, instead electing to remain in their temporary Academy on Shedu Maad.
Sometime between 40 ABY and 130 ABY, the Galactic Alliance and the Jedi allowed the Shaper caste of the Yuuzhan Vong to terraform the barren planet and restore it to its original beauty. A desolate part of the planet was chosen to test the Vong technology. Championed by Kol Skywalker and run by Master Shaper Nei Rin, the Ossus Project was a major success and soon, many planets turned to the Yuuzhan Vong to terraform their own planets.
However, sabotage by the One Sith eventually led to the Sith–Imperial War. In the wake of the war, the Galactic Alliance fell and the Empire ascended to power. The Jedi, refusing to follow the Empire and its Sith allies, retreated to Ossus. Nei Rin and several Yuuzhan Vong went to Ossus too, to study their work and find what had gone wrong on the project. The planet, however, had not been affected by any of the mutations that had occurred on other worlds.
The Sith, in league with Moff Rulf Yage, then attacked the Jedi Temple on Coruscant, and two days later struck again at Ossus. Amongst the Ossus Academy's defenders were Kol Skywalker, his son Cade, Wolf Sazen, and Shado Vao. On Kol's urging, Cade escaped the planet on a shuttle full of Padawans. Kol later fell to Darth Nihl, and most of the remaining Jedi on Ossus were slaughtered. Because the Sith attacked before all the Jedi could gather there, however, about half of them escaped and went into hiding throughout the galaxy. Cade, meanwhile, helped defend the shuttle from the Sith with his fighter, but when it was destroyed, he was forced to eject and was left behind. Cade was later rescued by the pirate Rav and his crew, and to spare his own life, Cade offered to show the pirates where the Temple's treasures were kept, claiming he was a scavenger who knew his way around Ossus. With Cade's help, Rav's crew looted the Temple and departed Ossus. The Empire later set up a watch on Ossus and routinely scanned the Temple for life. Rin and her warriors, who had been on Ossus but away from the Temple at the time of the attack, took refuge beneath the Temple, where they guarded a trove of Jedi artifacts.
Jedi in hiding
In 137 ABY, Cade Skywalker returned to Ossus. Imperial agent Morrigan Corde—secretly Cade's mother—and Sith agent Jor Torlin later arrived in search of him, but when Tol attempted to betray Corde, she killed him instead. Not wanting to see Cade again, Corde soon left the planet. Cade was later found by Jedi Master K'Kruhk, who had also been in hiding on the world. Along with fellow Jedi Wolf Sazen and Shado Vao, who had recently returned to Ossus expecting to find Cade, K'Kruhk helped Cade complete his Jedi training. During a sparring session, Cade and Shado discovered beneath the Temple Nei Rin and her Vong, and the lost vault of Jedi treasure they guarded.
Cade later left the world for Coruscant, while the other Jedi and the Vong stayed behind. However, they would not be left at peace. Someone in the Empire suspected that Jedi may have been hiding on Ossus, and Darth Stryfe was dispatched to the world. Joker Squad conducted a search of the surface, but found nothing, as the Jedi and Vong had gone into hiding. Nonetheless, Stryfe felt a stirring in the Force, and ordered the search to continue. The stormtrooper patrols at last left the planet, some having found no one, some having encountered the Jedi, but been mind tricked to believe otherwise. Stryfe still sensed a Jedi presence, though, and ordered the destruction of the Temple. His vessel opened fire, leveling the building.
Ossus was inhabited by intelligent life for unnumbered generations. In the days of the Old Republic before the Cron cataclysm, the planet's inhabitants were largely Jedi or other students of the Force. There was a large population of academics and scholars as well, taking advantage of the Order's tremendous wealth of knowledge. Members of nearly every species in the Republic could be found there. During times of war, the planet also played host to Republic soldiers, who used it as a staging ground to launch offensives into enemy space.
The supernova, however, changed this. Many of those who did not evacuate in time were killed when the shockwave hit. Those who had taken shelter in mountain caverns managed to eke out an existence on the now-barren planet. In time, they became the nomadic Ysanna tribes. Nearly all Ysanna felt the Force, but they were untrained, and their use of it was weak. However, it was enough to give them an advantage in their harsh environment, particularly in guiding the projectiles from their weapons to strike more accurately. A species of massive, hardy quadrupeds had survived the disaster too, and the Ysanna trained them as mounts. They adorned themselves in ritual masks based on artifacts of the dark side they had uncovered from the ruins of the Great Library. Though they had forgotten the specifics of their Jedi ancestors, they still held the ruins of the Order in reverence.
Other inhabitants arrived on Ossus in the intervening years, including those stranded by shipwrecks and the occasional squatter. Travgen, one of those who had chosen to come to Ossus, believed visitors to Ossus to be a threat to him, and attempted to scare off expeditions to the world. He did not, however, interfere with Luke Skywalker when he came, and was relieved when Skywalker left the planet. With the rediscovery of Ossus in 10 ABY and the eventual establishment of a new Jedi academy there, the planet once more became populated with Jedi. The Ysanna continued their lifestyle much as it was, now hosts to visitors from across the galaxy. Some Ysanna chose to join the Jedi and learn the ways of the Force. Less than half the Jedi in the Order were living on Ossus at the time of the Empire's attack in 130 ABY. In the time of the Ossus Project, Yuuzhan Vong warriors and shapers lived on Ossus as well. Almost all of them were killed in the attack on the Temple.
Knossa, located on a slope of the Eocho Mountains in the far south, was the primary city on Ossus and contained the planet's largest spaceport. It held the usual venues to be found in cities, including repair bays, restaurants, and lodging, and was also host to a number of research facilities for visiting academics.
Knossa's central plaza held two important obelisks topped with Adegan crystals. When the moons of Ossus aligned with the crystals, they produced a famous and magnificent display of light. The Jedi held this time to be sacred, and used it to remember those of their Order who had fallen in combat. It is from this that the term Ossus Day originated.
Great Jedi Library
Built by Odan-Urr in 4996 BBY, the Library was a great storehouse of Jedi knowledge, containing over ten thousand works. Located on a hill in the Eocho Mountains, the Library was a large, unadorned stone building with many of its rooms located below ground. Its entrances were unbarred, as Odan-Urr did not believe in fettering any being's search for knowledge. Though it was built for Jedi purposes, the Library held information on all subjects, not simply Jedi affairs, and access was granted to any individual who wished to learn.
Most data were stored in the main building, in a labyrinthine system of shelves. Reading rooms and classrooms filled the lower levels, as well as holograms of some of the most treasured contents of the library. Four towers held relics from the four main eras of history, as per Odan-Urr's dating system: Pre-Hyperdrive, Pre-Republic, Early Republic, and Mature Republic. More dangerous artifacts were stored deep underground, in the Chamber of Antiquities. Only those with permission from the Jedi Council and Keeper of Antiquities were permitted down there.
The Library's dense construction was likely what allowed it to survive the Cron supernova. Its location was lost until Rayf Ysanna's great-grandfather rediscovered it. He kept it a secret, not wanting the sacred ruins to be disturbed. Rayf revealed the library's location to Luke Skywalker on the Jedi's first visit to Ossus. The ancient secrets of the Jedi it still held were invaluable to Luke and his cause of rebuilding the shattered Order.
Located in a lush benchland between a mountain and a rift valley, and covering a wide expanse of land, the Ossus academy was the new nerve center of the Jedi Order after the Yuuzhan Vong War, replacing the destroyed Jedi Praxeum on Yavin 4. It was designed with meditation in mind; difficult paths between the buildings forced Jedi to focus on their surroundings and rooms in the Temple were arranged in a way that encouraged serenity.
Amongst the Academy's facilities was a massive lecture hall, a library, a hangar, training grounds, and laboratories. The grounds were staffed by Jedi, families of Jedi, and Ysanna. After it was attacked by the Sith and Empire, the Temple was left to the scavengers, who took many of its Jedi artifacts. Some Jedi and Vong hid within it in later years. It was destroyed by Darth Stryfe in 137 ABY.
Behind the scenes
The Dark Empire endnotes, where Ossus is first mentioned, give a different (and since superseded) history of the planet. According to them, Ossus was mysteriously abandoned circa 7000 BBY and decayed into ruins in the years after. The version of the endnotes included in the Dark Empire trade paperback gives the correct date of approximately 4000 BBY. It would not be until the Tales of the Jedi arc The Freedon Nadd Uprising that Ossus would be featured in a Star Wars work.