The Misty Mountains (also known by its Sindarin name of Hithaeglir - misspelled as Hithaiglin on the original Lord of the Rings map - and as the Mountains of Mist) are a mountain range, running for 1280 kilometers from north to south, between Eriador and the valley of the Great River, Anduin, and from Mount Gundabad in the far north to Methedras in the south.
Further geographical description
The northernmost peak of the Misty Mountains was Mount Gundabad, where according to legend Durin (eldest of the Seven Fathers of the Dwarves) awoke, though it was now an abode of Orcs. The greatest Dwarven realm in Middle-Earth, Khazad-dûm, was located at the midpoint of the Misty Mountains. The three peaks that were part of Khazad-dûm were Caradhras (Redhorn), Celebdil (Silvertine) and Fanuidhol (Cloudyhead). Inside Celebdil, the Dwarves built the Endless Stair, from the foundations of the mountain to the top of it. The southernmost peak of the Misty Mountains was Methedras (Last Peak).
Routes through the Misty Mountains
Routes around the Misty Mountains
The Gap of Rohan was the valley (probably of the River Isen) between the southernmost peaks of the Misty Mountains and the northernmost of the White Mountains. There may have been a gap between Mount Gundabad in the Misty Mountains and the westernmost extremity of the Grey Mountains, though published maps differ on this point.
Under the Misty Mountains are the former Dwarf realm of Moria and the Orc mines in which Bilbo Baggins stumbles across the One Ring. Rivendell was hidden in the foothills of the Misty Mountains at the western end of the High Pass. Carn Dûm, where the Witch-King of Angmar resided for several centuries in the Third Age, lay between a western spur of the northern extreme of the mountains, known as the Mountains of Angmar. Isengard lay centred around the tower of Orthanc in Nan Cúrunir between the arms of Methedras.
The great Dwarven realm of Khazad-dûm was once established beneath the Misty Mountains, but the unearthing of a Balrog in Third Age 1981 led to the desertion of this realm by Dwarves, though Orcs and other creatures came to dwell under the Misty Mountains.
The Fellowship of the Ring tried to cross the Redhorn Pass (after rejecting the High Pass leading to Rhovanion as being watched by the Enemy, and the Gap of Rohan as taking the Fellowship too close to Isengard), but a blizzard forced it to go under the mountain instead of over it. The Nine Walkers faced a Balrog, that dwelt in the deserted realm of Khazad-dûm. Gandalf slew the Balrog by throwing it from the Celebdil, but sacrificied his own life by doing this.