Tower of Amon Sûl

The Tower of Amon Sûl was built by Elendil in the founding years of Arnor, to hold one of the North-kingdom's three palantíri. It stood on the hill known as Amon Sûl or Weathertop, which at that time lay in the central parts of Elendil's northern domains. The later breakup of Arnor, though, left the Tower in exposed borderlands, and it was eventually destroyed by the invading armies of Angmar.