Great Temple (Yavin 4)

"I grow tired of asking this so it will be the last time: Where is the rebel base?"

- Grand Moff Tarkin to Princess Leia Organa

The Great Temple of Massassi, also known simply as the Great Temple, the Massassi outpost, or Base One, was a temple on the moon Yavin 4 that served as an Alliance to Restore the Republic base during the Galactic Civil War. In its struggle against the Galactic Empire, the Rebel Alliance had refitted the ancient-looking stone structure that notably contained a grand ceremonial chamber, a control room, and a vast hangar for starfighters. Following the Battle of Yavin, the Alliance evacuated the Great Temple and within three years, built and populated a new base of operations on the snow planet Hoth.

History
"These temples were built by the Massassi race thousands of years ago, and they’re still standing. Hard to believe."

- Leia Organa, to Luke Skywalker

The Great Temple was constructed over 5,000 years before the Battle of Yavin by a group of Massassi, a slave race once ruled by the Sith. It was surmised that the temple's site was either a holy place or a location significant for primitive scientific purposes.

The Massassi eventually went extinct, and over five thousand years after its construction the Great Temple was rediscovered by the Alliance to Restore the Republic who, having abandoned their former base on the planet Dantooine to evade detection by the Galactic Empire, used their engineers to convert the large structure into their base of operations, designating it Base One.

After successfully launching an attack on the Empire's Death Star from the Temple, the Alliance was forced to evacuate Yavin 4 for fear of retaliation. At some point following their departure, the Empire took over the Great Temple.

Layout
The Great Temple was a lofty pyramidal structure consisting of a number of successively receding stories and a high ceiling chamber at the top. It was built from huge blocks of stone hewed from Yavin 4's crust, with no visible signs of advanced machinery. After the Alliance to Restore the Republic took possession of the building, the Great Temple was arranged according to the needs of its new occupants. The interior walls were clad with sheets of seamed metal, new cavities were drilled, and the original stone floors were reinforced with ferrocrete.