Because I CBA to necrobump the old one.
QUARRIES: Essentially mines, but can be built anywhere (with the same materials as a mine) and are used for extracting boulders.
STONE WALLS: Castle walls, essentially. I'll leave the recipe to the devs, but it should have cornerposts as Turrets (perhaps more than one type of cornerpost, for different turrets and towers?) that can be entered and used as either raised vantage points for archery or the same as a cabin would be used. This is, of course, optional.
The gate for the castle wall should be a gatehouse, essentially. From the inside of the gatehouse, you can pull a lever to lower the Metal-Grate-thing (Look, I haven't studied medieval fortifications in forever) over the main gate.
Stone walls should only be able to be built by a super-dedicated team of villagers, or a village with a massive amount of manual labourers.
The stone wall should be nearly impossible to destroy by hand, even with a large team. But to combat UBERCASTLES, there should also be some sort of siege technology to counter the wall. Large battering rams to break open the gate, Ladders to scale the walls, catapults and Trebuchets... The possibilities could be endless.
I'd personally be happy with just quarries, though. Perhaps with traces of metal ore every now and then.