The Stone of Osgiliath was the greatest of the seven palantíri. It was housed in the Dome of the Stars for nearly 1500 years.

For the most part the palantíri were small and could easily be carried by one Man. This was not the case with the Stone of Osgiliath. It was larger than the rest and no Man could carry it.

The Stone of Osgiliath was the first to be lost. During the reign of Eldacar, the Kin-strife occurred, and the city of Osgiliath was taken and burned by the rebels. The palantír fell into the River Anduin and was never seen again.
Encyclopedia entry originally written by astro1014