Mystic Ruins

The Mystic Ruins (ミスティックルーイン) is a location that appears in the anime series Sonic X. Originally existing in Sonic's world, the Mystic Ruins, for a brief period of time, was relocated to Earth thanks to the effects of Chaos Control.

Past
Generations ago, the Knuckles Clan lived and thrived in this location. However, after the majority of the clan were wiped out by Chaos when they incurred the creature's wrath, the area was gradually abandoned, eventually being overgrown by the nearby plant life.

Chaos Emerald Saga
In the present day, the Mystic Ruins area got transported to Earth by a massive Chaos Control caused by the fight between Super Sonic and the E-99 Eggsterminator.

Chaos Saga
After being teleported to Earth, the Mystic Ruins became a popular tourist attraction to the human population over the next six months. It was also where Eggman first learned of the existence of Chaos and where Sonic learned of Perfect Chaos, both having learned through the stone tablets that had been left behind by the Knuckles Clan.

During the Chaos incident, Sonic and Knuckles were shown visions of the Mystic Ruins' past by Tikal and the Master Emerald's shards, and what exactly led to Chaos' anger and the destruction of the Knuckles Clan. Being the hiding place of the Final Egg, Sonic briefly visited the Mystic Ruins when giving chase to Eggman from the Egg Carrier. In what was supposed to be their final battle, Sonic caused the destruction of the Final Egg.

Homebound Saga
When it was revealed that the presence from everything from Sonic's world were threatening to freeze time, the Mystic Ruins and all else not native to Earth were sent back to their home world using a machine Tails and Chuck Thorndyke created.

Trivia

 * The Mystic Ruins is based on the location from the Sonic the Hedgehog video games.