I have been looking at the achievements and saw the tomes of dalaran one that requires you to read all the books in dalaran. I saw that you get to teleport to the top of a tower when you finish it and you can buy a mana wraith non combat pet.
So I figured hey, there's gotta be another way. Haven't made it there yet but this is my progress so far.
I used water walking and could mount on top of the water. Also I advise you purchase a parachute cloak because if you fall, it's a long way down.
The last screenshot is under the sewers, if you look while you are in the sewers you can see an arena match going on at the botton. You can get there.