Walls of Halruaa

The Walls were a crescent shaped mountain range that towered up to 20,000 feet (6,100 meters) over Halruaa. Prior to the Spellplague the mountains formed a natural defense for the realm. Unfortunately, the range's height made it difficult for Halruuans to escape the effects of the Spellplague. Three passes connected the remnants of Halruua to the rest of Faerûn.