Factorio Forums

Saw a barrier in survival, decided to check it out in god mode, and as you can see its a 'circle' round something. What is it that biters are trying to protect? Are all of them this smart? This is naturally generated, so be afraid, very afraid... (p.s. map isn't on the pic for whatever reason but it does show it as a circle with gaps in the N. S. E. W. ).

that's where you should build a large base to conquer the area

and see what their protecting