The Great Ring is a monumental magical object in the shape of a giant ring with the power of interdimensional travel by switching from one world to the next, and it first appeared in the animated TV series W.I.T.C.H..
The Great Ring is a gigantic ring that towers over the Palace of Meridian. It is used to create a huge fold that splits the castle in half between dimensions.
Its power supply comes from the Mage Ring and Blunk's Tonga Tooth.
It made its debut in "Y is for Yield" as the people of Meridian were forced to build the Great Ring over the palace. At the end of the episode, Phobos activated the Ring and a fold was created allowing a dozens of Lurdens and the Knights of Vengeance to cross over.
In "Z is for Zenith", Lord Cedric uses the Great Ring in order to invade Earth since he has grown to the size of Godzilla before he was crushed by the fully-evolved Guardians.
When Elyon returns back to Meridian with all her powers back, it is unclear of what becomes of the Great Ring towering over the Palace. It might be destroyed by her magic.