Voth Fortress Ship

The Voth Fortress Ship was a massive starship type in service to the Voth in the early 25th century. It was the primary source of ground troops in the Battlezone of the Solanae Dyson Sphere. The Allies were unsure how this 134.500 meters long vessel had entered the sphere.

Specifications
With a length of 134,5km, the Fortress Ship was by far the most massive starship encountered by the Allies in the early 25th century. Its interior was large enough to house a fleet of starships, and it carried dreadnoughts,  battleships,  cruisers, and  frigates. The interior was large enough to fit a Borg cube inside. (Star Trek Online official website: Season 8 Dev Blog #17, )

History
In 2409, at least one Voth Fortress Ship was stationed inside the Solanae Dyson Sphere. The Allies attacked it to disable the ship but could not destroy it because of the incalculable body count and possible damage to the Dyson sphere itself. The mission was led by Commander Schiesser of the Romulan Republican Forces. A flotilla a five starships was sufficient to take out the exterior weapon nodes before breaching the hull of the Fortress to gain access to its interior. The USS Bacchus (NCC-92780) was one of the Allied vessels participating in that endeavor. Inside, the flotilla fought a Voth fleet and moved through interconnected chambers separated by bulkheads large enough to let the flotilla fit through side-by-side. The flotilla targeted and destroyed a starbase-sized computer core to disable the Fortress without destroying it, and left through the hull breach.