Upper Blackrock Spire (Classic)

http://www.youtube.com/watch?v=teG_IhaTu7k might help people. I made it after trying to find the entrance for a while. Hopefully it helps someone that, like me, started playing in wrath and doesn't know the vanilla instances that well.

Make sure to obtain this achievement now, as it will become unobtainable in Warlords of Draenor. It will become a Legacy Feat of Strength along with Leeeeeeeeeeeeeroy!, so it is best to obtain both now.

Source: http://www.mmo-champion.com/content/4090-Warlords-of-Draenor-Alpha-Build-18443

Goblins are very lucky fellows. Cause we know that time is money.

So found a shortcut for us, Goblins. From the Rookery you can Rocket Jump to General Drakkisath's room. On the side where you can walk up are some ledges where can jump + rocket jump combo to reach the room of the final boss. With this you can skip the whole dungeon from the Rookery, this includes Blackrock Stadium.