Installing BAT Buildings
If you download buildings off from the official "SimCity 4" they buildings will automatically be placed in the correct folder, and be available the next time you start the game.
If download a building from a fan site, you will need to unzip (if the file is in .zip format) and put in the correct folder. Install new buildings to this folder (default installation location):
c:/my documents/simcity 4/Plugins
Using BAT Buildings
Some buildings are growable, which means you do nothing to make them be built in the game. The other type of buildings are ploppable. You must place the buildings yourself. Ploppable buildings generally include, but are limited to, education, health, safety, and landmarks.
Download BAT Buildings
