In Flame temple Corridor (Tyria), there's a corner with several portals set into the walls. You can't reach them, but they are clearly there.....and surrounded by Charr.
I'm pretty sure that when I first started playing GW just over a year ago, the rock in Sardelac Sanitarium covered the entrance to the catacombs. Last week I visited there again as part of the HM update, and I could see behind the rock, seeing stairs and stuff like that which I don't think were there before (in post.....obviously they are there in pre). Was this changed recently?