Barad-dûr is the fortress where Sauron rules Mordor in J.R.R. Tolkien’s mythology.
The name Barad-dûr means “Dark Tower” in Tolkien’s constructed language Sindarin. Sauron built it in Mordor during the Second Age, using the power of the One Ring to strengthen the tower and establish it as the center of his growing dominion.
The fortress stands near Mount Doom and serves as Sauron’s principal stronghold during the War of the Ring. Its great Eye is associated with Sauron’s searching awareness, although Tolkien’s books do not present it simply as a normal biological eye perched on the tower.
Barad-dûr is often confused with Orthanc, the tower of Isengard. Orthanc belongs to Saruman, while Barad-dûr is Sauron’s fortress. Minas Morgul is another major stronghold in Mordor’s wider sphere, but it is not Sauron’s central tower.