- 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 Triangular Wall. Place it inside your base.
Stone Triangular Wall
Triangular wall built on a foundation for keeping out intruders.
Made from stone, it is reasonably sturdy.