Weathertop is just a hill, but upon it Elendil built the watch-tower of Amon Sul in the Second Age. This was built to keep watch over Angmar, and the chief palantir stone was kept there. Weathertop was on the border of the three realms of Arthedain, Cardolan and Rhudaur, however, and as they became more and more sundered from one another during the Third Age, possession of the tower became contested. Rhudaur eventually became allied with Angmar, and in TA 1409, a combined force from Angmar and Rhudaur captured the tower and burned it. King Arveleg of Arthedain was slain defending it.