Elements of game design ,level design 

level design as what i can tell takes a huge amount of planning 

 and researching is key of course to find something really interesting that fits the brief the easiest way to do it is to find something that already exists because imaging something and having to design the hole world around so that make sense is alot harder. when we have so many things our history has already not to mention our planet has a vast amount of amazing places natural and mad made some of the natural things in life could look fantastic in game an make an awesome level.

like the alpes one of the most amazing sights ive ever experienced being at the top of a massive snow covered mountain.  

for another form of example some of the amazing environment art in farcry 3 set of the Indian and Pacific Oceans the artwork looks amazing lots of beaches and foliage .so far what ive seen of the game look like the best parts of the levels and really helps the gamer feel like somewhere else i chose this reference because its a mass of realistic natural elements i think during environment design a strong scene would be a mix of both man made an organic  aranged in a way that lets the game play flow well.

ive noticed in allot of games depending on the type of game which i think is massively important to know when designing a level,  is that they use man made things like crates and little shacks for the players to hide behind and take cover an shoot back ,because its a first person shooter .as well looking aesthetically pleasing the environment designer when planning out a level will know what parts of the level are destruct able but just from the this image looks like some really cool environment work.

after the research has been done an all the concepting been done alot of the time they do mock ups of the level orthographically images design laying out where things need to be, then "white boxin " 

just really quick white boxes laying out the level in 3d so that you can get a better feel for your level because its all well an good looking at your level on paper actually scrolling through or walking through in a game engine get a real sense of the game and what the audience will see. in and out of every process there would be art director of some sort helping you push your work further all the time so hopefully u can get the results that you want in the end .

i think  environment design a well as being art is a very technical function skill that is a very high end subject that takes a huge amount of experience and deserves allot of respect. as high for me as architect just for different purposes and you would have to have a high understanding of what your producing an technical aspects of things like architecture layouts and how the level flow is , and where your trying to get to and achieve in that level or scene 

http://far-cry.ubi.com/fc-portal/en-US/home/index.aspx

http://www.youtube.com/watch?v=pj8cbC2YnwU

http://jasonhalvorson.posterous.com/white-box-level-designing