The High Pass, also known as the Pass of Imladris or Cirith Forn en Andrath, was a pass over the Misty Mountains east of the elven refuge of Rivendell. Somewhere close to Rivendell a long, hard and dangerous path climbed into the mountains until it reached the mountain under which laid Goblin-town on its way to the High Pass. From the High Pass the ancient Old Forest Road descended to the Vales of Anduin to the river Anduin and then on into Mirkwood forest.
There were two passes near Goblin-town: the High Pass and another pass that was easier to travel. The main gate of Goblin-town was located near the easier pass. Because the Orcs of Goblin-town had often caught travellers who spent the night near the main gate at the easier pass, travellers stopped using this pass and used the High Pass instead. However, the Orcs created a new entrance in a cave near the High Pass.
In S.A. 3434 the main part of the army of Gil-galad, along with Isildur and part of the army of Arnor, used the High Pass, as well as the pass of Caradhras, to cross the Misty Mountains on their march to Mordor in the War of the Last Alliance of Elves and Men. After this war Isildur was slain on his way back from Gondor to Rivendell at the Gladden Fields by Orcs that had been sent there before the War of the Last Alliance by Sauron to watch the passes.
In the Third Age, the High Pass became dangerous again because of the Orcs. Only after the War of the Dwarves and Orcs, which nearly wiped out all of the Orcs of the mountains, did it become safe again. Nevertheless, in T.A. 2940, the goblins of Goblin-town had burrowed their way back to it, and Bilbo Baggins and the Dwarves of Thorin were captured there the next year during the Quest of Erebor.
During the War of the Ring, Grimbeorn the Old and the Beornings kept the High Pass open, but the Fellowship of the Ring ignored the High Pass because the eastern side of the Misty Mountains had become too dangerous.