Forge

From The StarCraft 2 Wiki

The Forge is the basic Protoss upgrade center. The Forge has the ability to upgrade ground weapons, ground armor, and plasma shields, which effects all of the player's units and buildings, except for those of other races acquired by Dark Archon's Mind Control ability. The Forge is also the prerequisite to build Photon Cannons in StarCraft I, which are the main static defense for the Protoss. The Forge will be the prerequisite for Photon Cannons in Starcraft II.

[edit] Upgrades

Ground Weapons 1: 100 minerals/100 gas

Ground Weapons 2: 150 minerals/150 gas

Ground Weapons 3: 200 minerals/200 gas

Ground Armor 1: 100 minerals/100 gas

Ground Armor 2: 175 minerals/175 gas

Ground Armor 3: 250 minerals/250 gas

Plasma Shields 1: 200 minerals/200 gas

Plasma Shields 2: 300 minerals/300 gas

Plasma Shields 3: 400 minerals/400 gas