Global Defence Initiative - Buildings  
Here is the complete list of GDI buildings in Tiberian sun with descriptions and pictures:  
Picture Upgrades Description
    Power plant is used for production of power for your installations. Power turbine increases power production for 50%.
      Barracks is used to produce infanrty units. It'a my advice to build this before building refineries.
      Converts tiberium into cash. Try to build at least two early in the game.
      Silo stores excess tiberium which you don't spend on building stuff. If you are a good player you won't need them.
      War factroy produces vehicles. Protect it well and if you have enough cash build a backup.
      It's advisable to build pavement arround your more important buildigs. That will prevent NOD underground units from surfacing near them.
      Wall is a great deffence of your valuable buildings from engineer attacks.
      Gate opens up only for your units.
      Very important building. Opens up a small tactical map in upper right corner.
Component tower with various upgrades. RPG is most effective against vehicles and vulcan is great against infantry.
      Disables enemy vehicles.
    Protects you against enemy missiles. It's very good but uses a lot of power and works for a short time.
      Build it as fast as you can because it enables you to build more advanced units and buildings.
      Enables you to build air units. It's a good idea to have more than one because it speeds up reloading process.
      Repairs your units and enables you to build MCV.
   

GDI upgrade center has two upgrades. Ion cannon is the most powerfull GDI weapon.
      Hunter seeker is automatic weapon which seeks enemy units and kills them.