The Mystic Ruins are the remains of a temple south of the Great Rainforest near Station Square and the Mysterious Cat Country. It is a large area with ancient buildings and trees. A long time ago, echidnas from the great Knuckles Tribe started a colony close by the Mystic Ruins after venturing from Albion. Desperate for the means to win a war the tribe was losing against the native Felidae, their chief Pachacamac, attempted to seize the Super Emeralds from the Ruins' altar, hurting many small creatures known as Chao, (and his daughter, Tikal) in the process. This angered the Chaos' guardian Chaos, and he destroyed the entire echidna settlement, turning its remains into part of the Ruins. Hundreds of years later, Dr. Eggman re-discovered the ancient temple ruins and began excavating it to locate and release Chaos from within the Black Emerald. Following its release, Chaos led Eggman to a mural depicting to him the means to restore Perfect Chaos. During the event of Chaos' reawakening, some of the shattered Master Emerald shards landed in the Mystic Ruins. As Knuckles explored them he encountered Tikal, who explained the history of her clan and the ruins. (StH: #81, #82)

The ruins later on became a secret location of a Dark Egg Legion chapter of cats and wolves lead by the joint Grandmasters Drago and Razorklaw (StH: #213)