Sol-Kathad; meaning the "The Frozen Tower" in elvish, was a large fortress located on the northern coast of the Sea of Adar.

The castle was built in the late Second Age by the Dark-Elves, and was once their northernmost outpost. During the Fourth Age, the kings of Thalar ruled from this castle and sat upon the Crystal Throne in its highest tower. This large castle was in a location so desolate that only the Thalari used it after the Drothë had left, and after the Storm of the North, it has never been inhabited by men again. Many sages believe that the Storm of the North began with the awakening of a terrible enemy in the crypts of the castle, and that danger then spread through the entire Northern Peninsula. Rumors exist that after the fall of Thalar, the Dark-Elves returned to the castle and rebuilt it, but these are not confirmed. In the Fifth Age, an army led by King Kren Alaghon attempted to besiege the castle and capture it. The siege failed, Kren was slain, and no further attempts were ever taken until 989/6, when King Morland Uzren II of Marundi attempted to rid the castle of its evil occupants. He too was slain and no further attempts have been made since.