The tower of Isengard, a pinnacle of unbreakable black stone built by the Numenoreans in the Second Age. Rising five hundred feet, its four pillars of rock meet at the peak in a flat platform used for observing the stars. Saruman takes Orthanc as his dwelling and uses the palantir housed within. Even the Ents cannot damage the tower when they destroy the rest of Isengard around it.