If found a way to climb on top of the roofs of buildings in The Military Ward in Ironforge.
The video shows how it is done. Step-by-step guide is below.
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-Go to The Military Ward in Ironforge, which is the room with the big coal pit, battleground room, and target dummies.
-Find the buildings in the video. They are located near the tunnel leading to Tinker Town.
-Mount up and walk up to the steps, turn right, and jump towards the wall.
-Dismount and jump up the crack between the wall and the building. (Jump, tap forward, repeat)
-Once you get to the top, there's a ledge blocking you from going any higher.
Walk forward a little bit to give you enough room to jump. Otherwise, you'll just move forward and fall.
-Turn around so you're facing the building behind you.
-Use Rocket Boots and jump forward to the ceiling of the building facing you.
(It might me possible to use Sprint or Blink, but I haven't tested those methods.)
-If you do it correctly, you'll stick to the edge. Jump to the top of to roof and you're done.
This can be very difficult if you don't have the timing right. It takes a lot of skill and luck to get up there.
I like to sit up there while I'm waiting for Battleground queues.
Since you now return to the location from whence you joined the BG, you can just chill up there between games.