Ithildin

A secret doorway that leads to The Mines of Moria, a Dwarvish mining area that's only shown in Lord of The Rings (The Fellowship of The Ring) and The Hobbit: An Unexpected Journey. The doorway is specifically locked, and can only be unlocked through secret magical spells from powerful wizards and possibly other powerful elvish beings (i.e Galadriel, Elrond, and much more). Gandalf The Grey specifically used many different types of magical spells by saying them out loud unlock the secret code that's labeled around the Ithildin doorway.