The Barrier Cities (バリアシティ, Baria Shiti?) are the result of Dr. Sid's invention in Final Fantasy: The Spirits Within. The Barriers, powered by bio-etheric ovo-pacs, protect the remaining human settlements on Earth against the Phantoms. The Barrier System Theory, developed in 2045, led to the creation of the Barrier City project, aimed at protecting the inhabitants from Phantom attacks through the use of spiritual energy control technology.
Barrier Cities began as military troop facilities. They were built seventeen years after the Leonid Meteor, which carried the Phantoms, fell on Earth. The first experimental small barrier city was completed in 2047. A total of 130 facilities were built across the world as a base operation for the troops of the United States Military Forces (USMF) in their combat against the Phantom threat. In 2048, Barrier City construction commenced for 130 cities and 1200 military facilities around the world. Due to the development of the Zeus Cannon in 2055, some of the Barrier Cities were not completed until two years later.
Human population began moving into the Barrier Cities due to the death of plant species, which depleted the world's oxygen. Oxygen generators were built within the Barrier Cities, and life outside these settlements became almost impossible.
List of Barrier Cities
The only known Barrier Cities are:
- New York Barrier City, the base operations of the New York United States Military Force, as well as the headquarters of the Council.
- Houston Barrier City, where the Council evacuated themselves after the Phantom attack on New York Barrier City.
- San Francisco Barrier City, which was attacked by Phantoms and where General Hein lost his wife and daughter.
- Chicago Barrier City, Gray Edwards's hometown.
- Tucson Barrier City, likely destroyed by the Phantom attack a long time ago; its ruins and remains of the barrier structure appear in the beginning of the Tucson Wasteland scene.