The fortress is the upgraded version of a stronghold.
As the military and economic center of the largest Orc cities, the Fortress can hold and process all the gold and lumber that the Peons can be made to harvest. Protected by obsidian spires shaped from the earth itself, the Fortress is all but impervious to the attacks of the feeble Human forces. Constructed by Orcish leaders attaining arrant mastery both on and off the field of battle, the Fortress serves as a proclamation to the Alliance of the inevitable triumph of the Orcish Horde.
Once orc technology reaches its height, construction of the Fortress may begin. Far more formidable than even the stronghold, the fortress provides a siege-resistant command base. With the addition of spiked barricades, a Fortress may daunt even the most hostile foe.
- Blackrock Spire (speculated, but represented as such in-game, and obviously similarly volcanic)
- Fortress Shadowmoon (explicitly described as looking like WCII style, but retconned)
- Fortress Auchindoun
- Grommash Hold
- Hellfire Citadel (speculated)