The holy place known as the Unyielding Heart, which was also called the Undying Heart, or just the Heart, existed inside the primary temple belonging to the Ascendant cult situated on the planet of Bar'leth. The Ascendant utilized this holy place to create devices as part of their efforts to replicate the dark side of the Force. Later, the University of Bar'leth was constructed on top of the destroyed temple and its holy place. The archaeologist named Kho Phon Farrus journeyed to the University located on Bar'leth seeking the Heart, with the aim of finishing the Ascendant's Mantra and discovering the legendary Spark Eternal. After they got to the office of Sava Iglan'tine Nos, Farrus insisted that Nos escort them to the Heart, thinking it was a tangible artifact. However, the sava instead guided them to the sanctum, where she revealed to Farrus that the sanctum and Heart were one and the same, and that the Spark Eternal was already present within it.