Tessida is a city on an unnamed Cylon-inhabited world that serves as a gigantic mainframe computing node for the Cylon Empire.
Tessida is located in the path of the entrance of the Canopus wormhole, which is of interest to Adama as it may hold clues to the location of the Thirteenth Tribe.
Tessida's ruler is Regent Abbadon (Battlestar Galactica: Cylon Apocalypse #2).
After Starbuck discovers a strange substance that effectively disintegrates Cylon technology, Adama chooses to weaponize it, attacking Tessida and destroying the Cylon's ability to attack the Fleet.
With news of a massive Cylon fleet approaching, the Colonials escape through the wormhole, gathering up the stranded Starbuck as they depart. For Abbadon, the news of the Cylon fleet is equally fatal as he knew that they would come to destroy what was left to avoid the nano-cybrid from further spreading thorughout the Cylon Empire. Abbadon self-destructs the fusion core in the Tessida mainframe, destroying the planet (Battlestar Galactica: Cylon Apocalypse #4).