In a later season, Rick’s group is led to a community called Alexandria. This town is filled with other survivors, thanks to tall, sturdy walls that protect the community. The towns’s founders used construction materials like wood and metal poles and metal panelling to construct the walls. One area also includes a covered sliding gate that allows residents to cross in and out of the boundaries.
Additionally, these walls are braced from the outside, a feature that makes the fence incredibly structurally sound. This bracing keeps the fence strong against hordes of zombies that congregate around it, and it affords the residents of Alexandria more room inside.