- Reach level 19, open the Technology menu and unlock Stone Structure Set for 3 Technology points.
- Collect what you need:
- Open the Build menu (B on PC), go to the Foundations tab, then Stone, and pick Stone Diagonal Wall. Place it inside your base.
Stone Diagonal Wall
An angled wall built on triangular foundations for keeping out intruders.
Made from stone, it is reasonably sturdy.