User blog comment:Extra-Planetal/Even more Reaper logic fails/@comment-1679409-20120428221838/@comment-156.26.175.99-20140507040745

For 2, it is the Leviathans that built the Catalyst, and the Catalyst that built the Reapers. Since the Catalyst used the Reapers to do it's work, it wouldn't be a far stretch to say that the reapers did indeed build the Citadel, both for their own use and to house the Catalyst; the Citadel itself is not the actual Catalyst, but a mere tool. (Need Leviathan DLC for some of this content) I personally think that in this matter they did a great job slowly leaking the knowledge and simulating the effects of the new knowledge on people's understanding of the old.