Mohit Malik hasn't finished his fortress wall material yet, but you already know it will be amazing. The procedural stones are this year's #Mayterials contribution and feature detailed customization: you can control the shape and size of the bricks easily by using sliders in Blender.
Some say this node tree looks scary, but I believe in creative chaos as long as the job gets done.
The fortress is still in development, so follow Malik on X/Twitter to never miss an update. You might also be interested in his mesmerizing tiles and wood carvings in Blender.