StarCraft/Protoss buildings

Nexus
The Nexus is the Protoss' primary building. It produces workers, and is where gathered resources are dropped off. A Nexus costs 400 minerals.

Assimilator
The Assimilator must be built on a Vespene Geyser before the Protoss workers can collect gas. It costs 100 minerals.

Pylon
The Pylon is the power source for all Protoss buildings (except for the Nexus and Assimilator). Protoss buildings require at least one Pylon built nearby in order to function properly. If a Pylon powering a building is destroyed, the building will stop working. A Pylon costs 100 minerals.

Gateway
The Gateway is where Protoss ground units (Zealot, Dragoon, High Templar, and Dark Templar) come out. It costs 150 minerals.
 * Prerequisites: Nexus

Forge
The Forge is used for upgrading Ground Attack, Ground Armor, and Shield Armor. It costs 150 minerals.
 * Prerequisites: Nexus

Shield Battery
The Shield Battery can be used by all Protoss units to recharge their shields. It costs 100 minerals.
 * Prerequisites: Gateway

Cybernetics Core
The Cybernetics Core is used for upgrading Air Attack, Air Armor, and increased attack range for Protoss Dragoons. It costs 200 minerals.
 * Prerequisites: Gateway

Photon Cannon
The Photon Cannon is a defensive structure for the Protoss. Its ranged attack can hit both ground and air units. It can also detect cloaked units. It costs 150 minerals.
 * Prerequisites: Forge

Robotics Facility
The Robotics Facility is the construction center for Shuttles, Reavers, and Observers. Only Shuttles are available by default.
 * Prerequisites: Cybernetics Core

Robotics Support Bay
Allows Reavers to be built at the Robotics Facility
 * Prerequisites: Robotics Facility

Observatory
Allows Observers to be built at the Robotics Facility
 * Prerequisites: Robotics Facility

Citadel of Adun
Allows the Templar Archives to be warped in
 * Prerequisites: Cybernetics Core

Templar Archives
Allows both High and Dark Templar to be built at the Gateway
 * Prerequisites: Citadel of Adun

Stargate
The Stargate allows air units to be warped in.
 * Prerequisites: Cybernetics Core

Fleet Beacon
The Fleet Beacon allows Carriers to be constructed, and allows Scouts, Carriers, and Corsairs to be upgraded.
 * Prerequisites: Stargate

Arbiter Tribunal
The Arbiter Tribunal allows Arbiters to be constructed and upgraded.
 * Prerequisites: Stargate and Templar Archives