Sauron’s fortress in Mordor is called Barad-dûr in J.R.R. Tolkien’s The Lord of the Rings.
Barad-dûr, whose name means “Dark Fortress,” is Sauron’s principal stronghold. It stands in Mordor near Mount Doom and serves as the center of his military power during the War of the Ring. The fortress is connected to Sauron’s will and cannot be permanently destroyed while the One Ring survives.
The Ring’s destruction causes Barad-dûr to collapse. This event follows Frodo and Sam’s journey to Mount Doom and marks the end of Sauron’s power in the story.
Barad-dûr is often confused with other major fortresses. Minas Morgul is a former Gondorian city occupied by Sauron’s forces, Orthanc is Saruman’s tower at Isengard, and Dol Guldur is a stronghold in southern Mirkwood.