The Great Assembly, a striking domed structure also known as the Great Assembly House, served as the home for the Planetary Council of Serenno, a planet within the Outer Rim Territories. This building was situated in the city of Carannia and prominently featured the Assembly Hall. Within this hall were the insignias of the seven Great Houses of Serenno, along with a sculpture of the Tirra'Taka, an ancient reptilian dragon.
The Assembly Hall endured for many generations, withstanding invasions, severe weather, and uprisings until 90 BBY. In that year, Dooku, a Jedi Initiate, and his sister Jenza, made a visit to the main hall. Dooku's focus was captured by the Tirra'Taka carving. Immediately after Dooku made contact with the carving, a powerful earthquake struck, resulting in the hall's destruction. Subsequently, several Jedi Masters and rescue droids saved the two siblings.
The Great Assembly House is a setting that appeared in Dooku: Jedi Lost, an audiobook considered canon. It was written by Cavan Scott and became available on April 30, 2019.