A massive complex in the middle of Borg space in the Delta Quadrant.

Apparently, Unimatrix One is the very center of the Borg civilization, and where the Borg Queen primarily resides.

In 2378, this complex sustained massive damage when a neurolytic pathogen was introduced into the Collective by Admiral Kathryn Janeway. It is not known if any portion of Unimatrix One survived this pathogenic attack.