The crystal control room. Located beneath Onrai square in the main city of Seoul 5 was the Crystal control room. This pivotal structure housed Seoularian crystals, which acted as the power source for the whole city. Prior to the Galactic Civil War's beginning, an Imperial scout extracted the primary Key crystal from its location; this crystal was essential for regulating the powers of the other crystals.
Following the Battle of Endor by a short period, Imperials, led by Captain Drezzel, came across both the city and the crystal control room. Fem Nu-Ar and Xathan, xenoarchaeologists who had traveled with the Imperials to study the ancient site, found themselves locked away in the control room. This was a consequence of their opposition to the Imperial scheme of utilizing the crystals for creating novel weapons. Han Solo eventually saved them after he won the key crystal from the Imperial scout during a card game. Through a strange sequence of events, Solo accidentally triggered an overload in the other crystals using the key crystal, which resulted in the control room's destruction.