Right so, everyone who has played a mage (or used unstuck) in WoW remembers the time when we could just blink thru shit and get to awesome places (Deadmines for example).
The same trick works in GW2 (Well, atleast was still working in the last Stress test which was way too short to keep my withdrawals away)
Best profession to do this with;
Thief with a Bow or that teleportation skill with a mad range.
The portal bypassing is pretty hard to do, requires a max range teleport to work.
TL;DR
1. Cast a teleportation spell behind A. An invisible wall B. A Portal C. A Model
2. You're behind it.
3. Explore, mess around, do stuff.
o/