The Vanguard complex
The Vanguard complex was a massive structure that orbited the planet Rkar N'ra in the Titan system along the Romulan Neutral Zone. The structure served as a source for the awakening of the Kam'Jahtae which were held in cryogenic suspension.
The complex became active when the USS Sentinel tested a new interspatial warp engines and revived the Kam'Jahtae. The complex is as much a space station as a starship; after its activation, it moved to the Tosk Nebula in the Norse system. It attempted to create a wormhole to Earth but was stopped by Ensign Ryan Cooper. It possessed powerful shields that made it almost impervious to attacks, however, a series of mines were able to disrupt the shield long enough for a Valkyrie class fighter to enter the ship.
The complex was equipped with plasma weaponry. (TNG video game: Invasion)