In an age now passed, the fire giants carved this fortress from the living rock of the Clawcrest Mountains, to be the mouth of the natural cave system they used as their lair. They were sorcerous pyromancers, whose use of the elemental plane of fire caused them to grow and swell to monstrous proportions, their skin turning black and red, their rages stoked like furnaces. For all that they became inhuman, however, they were still true wizards who realized their thoughts by force of will, and thus this fortress was created.
They saw much from the heights of their mountain fastness, watching kingdoms come and go, all the while growing fat off trade. Their feasts were replete with the finest spices in the world, their halls hung with the richest rugs and cloth. They had gold rings to decorate their bodies with, and more slaves than they could ever hope to need. All this and more they plucked from merchant caravans by way of taxes, tributes, and tariffs.
But that was then, and this is now. For the rat goblins grew covetous of their wealth and, even more, of their home. They were tired of cowering in their pitifully shallow, open-mouthed caves, but they had no knowledge of forts or castles. They had their shamans and their wizards, but since they are not true goblins but only called such, they are loath to engineer even structures of war and destruction. Thankfully for them, engineering the downfall of the fire giants required only magic and religion, and no construction at all.
After the giants were defeated and run out of their own fortress, the rat goblins wasted no time in making it their own. They brought their own goddess and their own types of fungus, but they also turned the bodies of the fire giants to their advantage as well — giving new “life” to their hands, their hearts, and their eyes.