Secrets of the Old City

From the introduction:

Almost every inhabitant of The City has heard that it was built upon the ruins of an older place – indeed, evidence of the Old City is everywhere. And rumors of its hidden treasures persist, even now.

The histories recount that the Old City was buried by cataclysmic ashes long before The Kingdom grew up to resume the industry of these parts.

However, few among the wisest scholars know that the Old City was itself founded upon an even deeper ruin – a far more ancient and treacherous place. None now recall who the Ancients were, or what disaster befell them...