The Gaia Temples (ガイア神殿,Gaia Shinden?), also known as the Temples of Gaia, are structures that appears in Sonic Unleashed. They are a set of seven ancient temples that are located around the world. By grasping the very power of the planet itself and the seven Chaos Emeralds, these temples have the ability to bring the whole world back together when it is broken into pieces by Dark Gaia following the time of awakening, and as well restore the Chaos Emeralds should they lose their power. They have a strong connection to Light Gaia.
The Gaia Temples are immensely large temples in various shapes. Their function is to harness the very power of the planet itself and work in sync with the Chaos Emeralds, with the purpose of putting the world back together whenever it is broken into pieces by the awakening of Dark Gaia and ultimately seal up Dark Gaia itself.
The process of restoring the planet and sealing Dark Gaia is through placing one of the seven Chaos Emeralds in a small altar found in the center of the temple. The Emeralds' power will then provide the energy needed for the Gaia Temples to help the Earth heal naturally from Dark Gaia's awakening. In the case the Chaos Emeralds have been drained of their power, placing them in the alter will cause the Emeralds to be recharged through the planet's power. In turn the act of the Emeralds being recharged leads to the equal and opposite reaction of the Emeralds healing the earth.
Since Light Gaia has been the one performing the process of restoring the planet since the beginning of time, it is unknown whether the Gaia Temples have always been used by Light Gaia to restore the planet since the beginning of his conflict with Dark Gaia (meaning they date back to the dawn of time) or they are only relatively ancient constructions made by an unknown builders for unspecified purposes.
Chip shares a special connection with the temples, due to the fact that they share the job of restoring the planet's condition, and they act as extensions of Chip himself. With Chip's innate Light Gaia powers, he can activate the central altar and reveal the pedestal for the Chaos Emerald to be placed, and can also sense the location of the temples after realizing his identity. It is within Adabat's Gaia Temple that his memory is restored by finding an apparent fragment of his essence inside it. As seen during the battle against Dark Gaia, Chip is able to call the Gaia Temples to his location in times of self-defense in order to form the Gaia Colossus.
The Gaia Temples were created ages ago to house the earth's power. Who or what created the Gaia Temples and for which purpose are unknown. The location of each Gaia Temple were eventually written in the Gaia Manuscripts following the time of awakening that occurred some tens of thousands of years ago.
In Sonic Unleashed, Dr. Eggman learned about the Gaia Temples from the Gaia Manuscripts. After somewhat successfully awakening Dark Gaia with his Chaos Energy Cannon and splitting the earth apart, the doctor sought to secure the Gaia Temples as they could prove to be a threat to his plans. Meanwhile, Sonic the Hedgehog and Chip (aka. Light Gaia) began to seek out the Gaia Temples in order to restore the planet and stop Dark Gaia's resurrection. When Eggman learned Sonic was still alive after their last encounter, he deployed his forces to the Gaia Temples to slow down Sonic while completing his plans with Dark Gaia's energies. These efforts proved to be in vain, as Sonic and Chip were successful in reaching all seven temples, stopping the doctor's plans and putting the world back together.
In the process of the restoration of the final continent, the Gaia Temples were all called together by Chip to form the Gaia Colossus in the insuring battle with Dark Gaia, and later Perfect Dark Gaia. All of the Gaia Temples (still combined into the Gaia Colossus) were later, presumably, destroyed as Chip was resealed inside the earth's core following the defeat of Perfect Dark Gaia.
Eggmanland: Unguarded, although the player does fight Dr. Eggman's Egg Dragoon after restoring this temple.
As shown on the PS2/Wii version of Sonic Unleashed, each Gaia Temple (except the one in Eggmanland) has one or more appointed human guardians, named "Temple Guardians", who watches over the Gaia Temples and deem whether a person are worthy to use the Gaia Gates that lead to the temples. These people are the latest in a long line of guardians who have watched over the temples since ancient times. These people are also the only ones who can assemble a Planet Tablet. The following known guardians are:
Each temple has the Chaos Emerald on the Earth's continent to restore a powerless one: Green - Mazuri, Red - Chun-nan, Blue - Spagonia, Cyan - Holoska, Yellow - Shamar, Purple - Adabat and Silver - Eggmanland.