How to get to Fortress Mechanotus

The fastest way for you to reach Fort Mechanotus is by taking the Guild Hall to Dragonscale Hills and then traveling northeast from where you zone in to the large machine that catapults you up to Fort Mech. You can also get a Wizard or Druid to portal you, if you don't have access to the Guild Hall.

In the northeastern most corner of Dragonscale Hills near the gnome/clockwork gnome encampment you'll find a large machine with a catapult on it, shown in my screen shot below. Step onto the pad to be launched high into the sky to Fortress Mechanotus.