The tower in Isengard in J.R.R. Tolkien’s The Lord of the Rings is called Orthanc.
Orthanc is a tall, dark tower built by the Dúnedain of Gondor in the Ring of Isengard. It stands within a fortified circular plain and was originally used to guard the Gap of Rohan. Saruman occupies it as the chief of the Istari and uses Isengard as a base for military production and political manipulation.
The name Orthanc has a deliberate double association. In Tolkien’s invented language Sindarin it is often explained as meaning “Mount Fang,” while in the language of the Rohirrim it can be understood as “Cunning Mind.” Orthanc is not the same structure as Barad-dûr, Sauron’s fortress in Mordor, or Minas Tirith, the great city of Gondor. Its distinctive black stone and unbreakable construction make it one of Middle-earth’s most recognizable towers.