What is the name of the tower of Sauron in Tolkien’s land of Mordor?

The tower of Sauron in Tolkien’s land of Mordor is Barad-dûr.

Barad-dûr, whose name means “Dark Fortress” in Sindarin, is Sauron’s principal stronghold during the Second and Third Ages. It stands in Mordor near Mount Doom and is built around Sauron’s power. The fortress was first constructed during the Second Age and was destroyed at the end of that age after the One Ring was cut from Sauron’s hand.

Sauron rebuilt Barad-dûr in the Third Age, and it remained the central symbol of his rule until the Ring was destroyed. The tower is different from Orthanc, which is the tower of Isengard, and Minas Morgul, a former Gondorian city controlled by Sauron’s servants. Barad-dûr’s collapse after the Ring’s destruction marks the final defeat of Sauron in The Lord of the Rings.