Doorward

Doorward is the location in which Baelgun Flamebeard and the Bronzebeard Expedition have selected for their camp in Azjol-Nerub. He and the other dwarves have fortified it heavily. They also have several barrels of explosives ready in places around the camp. From the camp, they have a good view of the tunnel leading up to the surface. Behind him is the massive, blood red door leading down to the depths of the Old Kingdom. The door is locked, and Baelgun holds the Blood Key that opens it. The dwarves at Doorward had been attacked by Arthas Menethil when he traveled through the Old Kingdom a couple of years before, but most survived their wounds.

Trivia
Doorward is not the only way into the Old Kingdom. The Scourge had discovered a second entrance to explore. This does not bode well as it is believed that the faceless ones would easily overpower the undead and escape to the surface.