Fire and brimstone and a bone dragon, oh my

This black castle by Aaron Newman which he calls Grimstone is a delightful blend of classic fantasy and a bit of industrial revolution, with smokestack-looking towers, and a hint of castle Greyskull, with those black claws flanking the main gate. The sloping bridge over flaming hot magma leads to a dilapidated town that is looking a bit worse for wear. I also love the many shades of orange plates used for the lava.

Grimstone Fortress