Ziggy Stardust gateway

The Ziggy Stardust gateway was a large opening to the Appaloosan Mountains carved by a presumably long-lost branch of the Diamond Dog culture in Equestria. The gateway was passed by the Mane Six during the second Changeling war when they made their trek to the Changeling Kingdom by the day of the Secretariat Comet in order to save the Cutie Mark Crusaders. Pinkie Pie found Mr. Bones while in the archway.

It is named after Ziggy and Stardust, which in turn is a reference to David Bowie.