I can't find /Library/Frameworks on Mountain Lion. Is somebody having the same issue?

I am using Mountain Lion and I managed to unhid the Library folder. I was downloading packages from the net and according to the R terminal the packages are stored in

"/Library/Frameworks/R.framework/Versions/2.15/Resources/library"

but when I go to the Library folder I can't find the Frameworks directory.

Somebody has any suggestions on where to search for the /Library/Frameworks ?

Thanks