Forge

The forge is a site of protoss technological development. Although their technology is incredibly advanced when compared to that of other species, the protoss constantly strive to enhance and refine their weapons and armor. Work at the forge rarely ceases, as this edifice is where much of the research takes place.

StarCraft
The forge upgrades the armor and weapons of protoss units along with the plasma shields on all protoss units and buildings. The forge allows access to the photon cannon.

StarCraft II
The forge reappears in StarCraft II.

Co-op Missions
Karax unlocks upgrades for his static defenses at the forge when he reaches Level 6.