IsengardIsengard was a city and its surrounding fortifications in J.R.R. Tolkien's Middle-earth, located in a valley between Rohan and Fangorn. At the center of the city is a tower known as Orthanc which appears to consist of natural pillars of rock, but was in fact fashioned by cunning hands many centuries before. During the Third Age, it was inhabited by Saruman the White, from whom is derived the valley's name of Nan Curunír, Curunír being the elvish equivalent of Saruman.
Isengard is the city's name in the language of Rohan. It is a translation of the Sindarin name Angrenost meaning "Iron Fortress".
Isengard (or better, the tower of Orthanc) possibly is one of the places which gave name to the second volume of The Lord of the Rings, which is called The Two Towers. However, there are other candidates, and Tolkien states in one of his letters that he deliberately left the title ambigious.