At first it was the second and more to the west
Home to the lieutenant who survived the sack
then it was made far superior to all the rest.
From here the great miseries spread
While the Black Enemy sat in his pit of dread
til all was lost to the great sea bed.
Angband
Originally Melkor had his base in Utumno, establishing Angband as a secondary fortification. Sauron was in charge there (at Angband) and he kept Angband nice and cosy until Melkor returned with the silmarilli.
Tolkien Gateway: Angband