Grimrock

Apologies if this is not the right place to ask this. I need help finding access to these two areas. How do I get to the area that looks like an inverted U here on this screenshot of the middle level of Crystal Mines:

http://i.imgur.com/8YGcpUC.jpg

And how do I get to the area behind this wall in the top level of Crystal Mines. I can hear one of those floating fire knights right behind this wall:

http://i.imgur.com/6tG1STQ.jpg

I'd be grateful for any help-

put this in gameplay hints section and you should get more responses.

the second one is in the room south of yours. there is a hidden switch near the cristal. the first one is also a secret switch i think. the mines have very small hiden switches. you should really pay good atention to them