In the northern reaches of the Eastern Kingdoms sits the city of Stratholme
Once a border city of the Kingdom of Loarderon, Stratholme was infested with the plague by Mal’Ganis as part of a plot to lure Prince Arthas to Northrend. It’s citizens were turned into mindless undead and the city fell.
Added in vanilla, Stratholme was one of several inaccessible zones in the game. However, with the reworking of Azeroth in Cataclysm, combined with the addition of flight, Stratholme alone remains hidden by an invisible wall that blocks access to the city from all directions.
While you can enter Stratholm via the dungeon version, the zone appears to consist of an uninstanced version which cannot be reached by players. However, some argue that the zone is too big to contain Stratholm, a relatively small city.
Another possibility is that the zone was meant to be an expanded version of Deatholme.
Deatholme, a scourge city which hosts a questline in Ghostlands, sits directly above the hidden zone on the map. There are theories that early in development, Deatholme was expanded into a larger area, hosting a longer questline.
Marking the end of the Dead Scar, a path of destruction leading to the point where the undead laid siege to Silvermoon City, Deatholme feels like a zone intended to be larger than it is. It looks like the beginning of a small city, with elevated buildings, a large entrance gate, and a looming ominous feel. However, the city abruptly stops at the back wall, blocking entry into what would be the inaccessible zone.
Is it possible that the city was meant to be much larger than it is in-game? Receiving its own small zone with a questline discussing it’s relation to the siege of Silvermoon.
Unfortunately, we may never know. As the true purpose of the zone remains a mystery.
I managed to get into this zone, which the game calls Quel’thalas, using a trick from some video I saw (I think it was vaulty but I have history off so I’m not sure). Basically you run in and out of the Stratholme dungeon a bunch of times and reset it until it doesn’t let you in anymore. Then you use a class ability (I used the DH leap) to get through the invisible wall and you can go through non-instanced Stratholme to where Rivendale would be. From there you go through the gate that big group of zombies comes out of and you get to this unfinished area with an untextured Naxx and you can walk through the walls to a zone called Quel’thalas. It’s mostly just hills but there’s some night elf ruins on the North shore and you can get to a part that looks like the Ghostlands but has almost nothing there except for a few scourge flags, a blood elf cart, and one of the buildings from Deatholme. I feel like they were probably going to have Quel’thalas as part of the Eastern Kingdoms at some point in early design or while they were working on BC but then didn’t for some reason. You should totally check it out.