I was looking at the official Half-Life 2 site today and noticed this:
Then I found these two screenshots of the Citadel.
(don't know if they qualify as spoilers anyways, just images of the citadel)
So, it accured to me that the Citadel resembles giant mining facility /...
no ghosting or blurring. the thing that bugs me is the refresh rate. it's like 65hz or something. it's quite annoying / distracting when playing games.