Nice work! If I were you, I'd stretch some outer segments to make them look more solid rather then ladder-like (like you did in your Icecrown variation). Like Necropolis has a blueish piece under bronze crossbars that is meant to stay on a brick-textured part. The ideas are cool and they also can inspire one to take your works and add protection on top of the mines just like in upgraded Ziggurats

Edit: Icons added and updated Boneyard version

optimizations: calculate extents

Review accepted by Footman16