Dragonspear Castle

Dragonspear Castle was originally a dwarven fortress built upon the High Moor, but has long since been destroyed. Its ruins serve as a landmark on the Trade Way, but the fear of what could be inside keeps all but the bravest or stupidest from its gates. While originally built as a dwarven stronghold and to be a lair for a bronze dragon, those days are long past.
The legends are well known. Dragons clashed in the skies overhead. Devils from the hell of Avernus have entered through a portal in the depths of the castle. Hobgoblin bandits using the castle as a hideout. A zealous Aasimar leading an army of holy warriors. All have had to be defeated by adventurers, heroes, and the armies of Baldur's Gate and Waterdeep. The rumors say the portal to hell deep below the castle has not been destroyed, but merely lies dormant, awaiting its reactivation by those who would bring the forces of hell back to the Sword Coast.