- "Luke, this is the entrance that leads underground to the Lost City of the Jedi. The entire history of the galaxy and all its worlds is recorded there, protected by the caretaker droids of the city. Your destiny is linked to one who lives down there."
- ―Obi-Wan Kenobi
The Lost City of the Jedi was a secret city and terraforming station, located deep below the surface of the fourth moon of Yavin Prime. Thousands of years before the rise of the Galactic Empire, at the end of the Great Sith War, members of the Jedi Order chased the renegade Exar Kun to Yavin 4. Wishing to obtain the demise of the Sith and bring the war to an end, the Jedi launched a salvo of destructive energy at the moon, trapping Kun's spirit in his temple but ravaging the surface of Yavin 4 in the process. This environmental catastrophe completely destroyed the ecosystem of Yavin 4, and the Lost City of the Jedi was built to nurture the world back to health.
The terraforming of Yavin 4
- "Looks like we've defeated Exar Kun... ...but at what cost?"
- ―Nomi Sunrider
Around 4000 BBY, a rogue Jedi apprentice named Exar Kun partnered with the Krath cult to form the Brotherhood of the Sith, in hopes of bringing down the Galactic Republic and the Jedi Order. Kun had been christened the new Dark Lord of the Sith by the ghost of Marka Ragnos, and had established his quarters on the fourth moon of Yavin Prime. The series of battles that ensued, known as the Great Sith War, resulted in millions of deaths. Four years later, Ulic Qel-Droma—a fallen Jedi and ally of Kun—betrayed the Dark Lord and revealed the secrets of Kun's power base. Soon, a legion of Jedi, led to Yavin 4 by Qel-droma, arrived to stop Kun and bring the war to an end.
Unyielding, Kun decided to drain the life of thousands of Massassi so he could trap his own spirit into the walls of a temple. Determined to end the war, the Jedi banded together and created a wall of light, a devastating salvo of light side energy, which they launched at the planet. This powerful combined attack accidentally ignited the moon's jungles, causing the deaths of the few remaining Massassi, levelling most of the temples and razing the rain forests to the ground. Kun's spirit had been trapped inside his own walls, but the ecosystem of Yavin 4 had been ravaged in the process.
The Jedi Order sought to reverse the damage their wall of light had caused and established an underground terraforming station that would restore the moon to its former state. Following the fires, the landscape of the moon had become barren and cold, but a group of Jedi Masters discovered they could change the climate by creating a way to bring heat from the moon's core to the surface. This involved drilling deep shafts into Yavin 4 which were designed to release steam as well as heat into the atmosphere. This in turn led to the development of the Weather and Climate Command Center. Once established, the Center manipulated the moon's environmental conditions, which in turn, made the moon warmer and more tropical. Once this was done, the Jedi began seeding the four continents, thus allowing lush forests to grow again on Yavin 4.
Upon the completion of this terraforming process, the Jedi began to make arrangements for a subterranean city which, in time, would become known as the Lost City of the Jedi. The settlement was created on the moon's largest continent, and it was built deep underground, below the rainforest, in a huge cavern. Using deep shafts similar to the ones they cut to release the heat in the moon's core, they created tubular transports that allowed for travel between the underground city and "Topworld"—which was the name given to the surface. One method of entry was a round wall made of green marble which was located in the forest. Inside the underground cavern were numerous dome houses that housed Jedi Knights as well as various pieces of advanced equipment. Beyond its ecological importance, the new city also had the function to guarantee the spirit of Kun would never break free.
From history to legend
- "Of all the explorers who have searched for the Lost City. I don't know of any who has lived to tell the tale."
- ―Zorba Desilijic Tiure
At some point after the founding of the city, the organic inhabitants left, and an army of droids took over the care-taking of the settlement. The facility consisted of travel tubes, computer cubes as well as droids of every possible design. This high degree of automation meant that the city was highly busy due to its droid occupants who were always modifying the computers, making new droids or repairing old ones and doing other maintenance duties such as working on the power generators, cleaning as well as maintaining the hundred domes that dominated the city. In time, the city became forgotten and was considered nothing but a legend in the centuries that followed its creation. Nonetheless, the city remained active and its droid occupants would, on occasion, journey to the surface of the moon and gather information which was used to update the history of the galaxy for the Lost City's Jedi Library.
Around the year 7 BBY, an unknown brown-robed Jedi Master brought Ken, the supposed grandson of Emperor Palpatine, to the city to keep him safe. For twelve years, the boy grew among the droids of the Lost City, away from the dangers of the dark side but in the ignorance about his origins. Following the Battle of Endor, the Bimm impersonator posing as the Supreme Prophet Kadann intended to get his hands on the ancient knowledge hidden in the Lost City. In order to find the location of the famed and forgotten city, the false Prophet abducted the young Prince Ken. He promised he would reveal the secrets of the boy's origins if he was told the correct geographical coordinates of the Lost City. Ken was troubled by this promise, and he gave the pseudo-Kadann the information he sought. The Jedi secrets contained in the city's master computer almost fell into the fake Prophet's hands, but the Grand Computer was destroyed by blaster fire, leaving Kadann and his minions inside the crumbling city. Although they eventually escaped, the city itself had been damaged enough that Exar Kun was now free to wander the entire moon.
The Lost City was built several miles below the surface, in a cavern lit up by bubble lights and fluorescent rocks. Most of the city's buildings, where the Jedi used to live, were dome-shaped. The city was criss-crossed by roads made of perfectly cut stone.
Within the Lost City of the Jedi was a great library which possessed records that dated back for thousands of years. The majority of the records were located within a master computer that possessed files placed in there by the Jedi. In addition to these electronic records, there were also ancient manuscripts as well as books. Inside this repository of knowledge was information of all civilizations and the history of all planets as well as moons that had intelligent life on them.
Weather and Climate Command Center
The complex facility was developed by the Jedi thousands of years ago and placed within the Lost City. It consisted of a series of pipe shafts that tapped into the moon's core and brought heat as well as steam to the surface. This allowed a level of control over the weather patterns of the moon and allowed it to be transformed from a barren wasteland into a tropical forest planet. Through a special code, the computer was capable of being accessed, and directed to release steam, thus creating new climate changes such as bringing the rain season early.
- The Lost City of the Jedi (First appearance)
- Zorba the Hutt's Revenge (Mentioned only)
- Mission from Mount Yoda (Mentioned only)
- Queen of the Empire (Mentioned only)
- Prophets of the Dark Side
- "Star Wars Publications Timeline" – Star Wars Insider 23
- The Essential Guide to Characters
- Star Wars Encyclopedia
- "Who's Who: Imperial Grand Admirals" – Star Wars Insider 66
- The Official Star Wars Fact File 15 (YAV3, Yavin 4)
- The Official Star Wars Fact File 75 (JED4, The Jedi)
- The Official Star Wars Fact File 134 (LIB2, Libraries)
- The New Essential Chronology
- Knights of the Old Republic Campaign Guide
- The Complete Star Wars Encyclopedia
- The Essential Atlas