You can also access any archived thread by typing http://cplusplus.com/forum/board/number. It doesn't matter what board you put, you'll be redirected automatically.
Oh yeah, it is on that page, it's just not on the navigation menu on the left.
Still, the other thing I discovered is pretty cool. This is the first non-admin post ever: http://cplusplus.com/forum/articles/7/ (or at least, the first archived one). If you replace 7 with a number from another board, then it changes to the correct board automatically (for example if you put /articles/20/, it will change to /beginners/20/).