Morannon

The Morannon, known as the Black Gate of Mordor, stands as an impregnable fortress guarding the sole northern entry into Sauron's dark realm, its massive iron gates and towering battlements symbolizing the Enemy's unyielding might. Introduced in The Two Towers as a daunting barrier patrolled by orcs and sentinels, it evolves into a pivotal battleground in The Return of the King, where Aragorn's desperate Army of the West mounts a diversionary assault to distract Sauron from Frodo's quest at Mount Doom. Though it sees no further direct action beyond these climactic moments, the Morannon's fall amid the collapse of Barad-dûr marks the dramatic end of Sauron's dominion, transitioning from an ominous threshold to a shattered ruin.