Luna

Luna is Terra's only moon and a gun-belt for the Throneworld, with shipyards and a broken defensive ring still covering the inner system. Selenar gene-cults once ran its vaults; the Emperor broke them in the First Pacification of Luna so the Legiones Astartes could be mass-produced. Sisters of Silence later held the Somnus Citadel here, and the moon has been fought over again in the Solar War and during Guilliman's return.