Sauron's main fortress and tower in Mordor. Work on it was started in about the year SA1000, right after Sauron chose Mordor in which to make his stronghold. Barad-dûr was completed in the year SA1600 - the same year that he forged the One Ring. In SA 3441, Barad-dûr was laid to ruin after a seven year siege by the Last Alliance of Elves and Men, when the Ring was cut from Sauron's hand by Isildur.

In TA2951 Sauron began rebuilding Barad-dûr on the foundations of the original fortress. He ruled from there until the Ring was destoyed in TA3019. Upon the destruction of the One Ring, Barad-dûr crumbled as the sorcery and power that was used to aid in the construction of its foundations was destroyed along with the Ring.