Barad-dûr is Sauron’s fortress in Mordor in J.R.R. Tolkien’s Middle-earth.
The name is Sindarin and is commonly translated as “Dark Tower.” Barad-dûr stands near Mount Doom, where the One Ring was forged. Its location makes it the political and military center of Sauron’s power during The Lord of the Rings.
The fortress was originally constructed in the Second Age, during Sauron’s rise in Mordor. When Sauron was defeated at the end of the Second Age, Barad-dûr was destroyed, but its foundations endured because they were bound to the power of the One Ring. Sauron rebuilt it in the Third Age.
Barad-dûr is often confused with Minas Morgul, another major fortress in Mordor, or with Orthanc, Saruman’s tower in Isengard. Cirith Ungol is a pass and a tower near the route toward Mount Doom, not Sauron’s main stronghold.