Collect the Conspiracy Data Disks. You will unlock a concept art gallery for every ten disks collected. There are a total of six galleries that can be unlocked.

Gallery 1: Collect 10 disks.
Gallery 2: Collect 20 disks.
Gallery 3: Collect 30 disks.
Gallery 4: Collect 40 disks.
Gallery 5: Collect 50 disks.
Gallery 6: Collect 60 disks.