The Forbidden Mountain is a dangerous mountain region where Maleficent's Castle is located. It serves a the home to the evil fairy Maleficent.
The Forbidden Mountain is a range of mountains with a ruined castle at its peak that serves as Maleficent's home. The surrounding sky is generally pale green in color and the entire area has a dark atmosphere. The Forbidden Mountain is thought to be one of the gloomiest and darkest places to live.
Maleficent lived in an eerie castle within the Forbidden Mountain throughout her life, ruling over her own subjects, harnessing her dark magic, and scheming against King Stefan and his daughter Aurora.
When her goblin soldiers reported back to her about Princess Aurora (only they were searching for a baby) with no such luck, she became frustrated and ordered them to leave her in her throne room. She and her pet Diablo take matters into their own hands and left Forbidden as they went to find Aurora and complete her dreaded curse of permanent sleep upon the unsuspecting princess on her 16th birthday.
The mountain is also the place where Maleficent kidnapped Prince Phillip and locked him in her dungeon, in order to prevent him from rescuing Princess Aurora and breaking the spell. The Three Good Fairies however, manage to sneak inside the castle and rescue him. They give him the Sword of Truth and the Shield of Virtue as he will encounter many dangers ahead.
When Maleficent finds out that Prince Phillip has escaped, she does everything she can to prevent him from reaching King Stefan's Castle.
Despite Maleficent's main domain being the Moors, the Forbidden Mountains make a cameo in the live action adaptation as the ruined castles that Maleficent takes refuge in after Stefan steals her wings.
The Forbidden Mountain makes many appearances in Once Upon a Time. A part of the Enchanted Forest, it is within the borders of King Stefan and Queen Briar Rose's Kingdom and was home to Maleficent. Regina would often make many visits here to seek the counsel and advice of Maleficent.
The Forbidden Mountain make's an appearance in Once Upon a Time in Wonderland episode Forget Me Not.
It was were the Looking-Glass of Wonderland was held. Robin Hood, Will Scarlet and the Merry Men all raided the fortress in search for gold. Will himself had planned the raid as a distraction so he may search for the Looking-Glass and the ability to cross dimensions so he and his Anastasia could escape the Enchanted Forest for a new realm, Wonderland.