The isolation chambers were concealed areas situated within the subterranean galleries under the temples of Yavin 4, structures erected by Naga Sadow. Their function was to house the Massassi warrior Kalgrath, who was placed into a state of suspended animation in 3996 BBY. Within these chambers was a capsule for suspended animation, along with a rudimentary computer that held a portion of the Massassi's historical records. A clandestine underground passage leading to these rooms was concealed behind an unmarked wall in the main hall of the Great Temple, an area that had been transformed into the Massassi Station's hangar by the era of the Galactic Civil War.
Not long after the Battle of Yavin, a TIE/sa bomber starfighter belonging to the Galactic Empire met its end in a crash amidst the Massassi ruins, leading to damage within the isolation chambers and the subsequent awakening of Kalgrath. Luke Skywalker, the hero of the Rebel Alliance, employed the Force to reveal the unmarked wall, thereby discovering the isolation chambers and gaining knowledge about the ancient Massassi civilization and their final protector.
The 2001 roleplaying sourcebook The Dark Side Sourcebook indicated that the isolation chambers resided beneath the Temple of Fire, while the 2008 reference book The Complete Star Wars Encyclopedia suggested their location was in the lower sections of the Great Temple.