Barad-dûr is the tower fortress of Sauron in J.R.R. Tolkien’s Mordor.
Barad-dûr, whose name means “Dark Tower” in Sindarin, stands in Mordor near Mount Doom. It serves as Sauron’s principal stronghold during the events of The Lord of the Rings and is closely associated with his military power, surveillance, and control of the surrounding land.
The fortress was originally built during the Second Age, when Sauron established his power in Mordor. After the One Ring was cut from Sauron’s hand at the end of the War of the Last Alliance, Barad-dûr was destroyed, but its foundations remained. Sauron rebuilt it when his power returned in the Third Age.
Barad-dûr is often confused with Orthanc, the tower occupied by Saruman in Isengard. Minas Morgul is another major fortress in Mordor’s wider region, but it is the corrupted former city of Minas Ithil rather than Sauron’s principal tower.