The watchtower in the middle of the River Sirion, first looked after by Finrod and then Orodreth after the delving of Nargothrond.

Just after the Dagor Bragollach, Sauron and his forces stormed the watchtower, driving out Orodreth. He then turned it into a place of horror and nightmare, called either the Isle of Werewolves or Tol im-Gaurhoth. Beren and Finrod were later kept in the dungeons below the tower.
Encyclopedia entry originally written by atalante_star