Has Any Country Never Built a Border Wall?

Every sovereign nation maintains some form of border control—whether physical barriers, natural boundaries, patrols, or legal frameworks. The idea of a country with zero border defenses is a myth. Even nations with open-border agreements (like Schengen) have external controls. Walls, fences, rivers, mountains, and monitored checkpoints all serve to regulate entry. So, no country has completely avoided constructing defenses to protect citizens and control crossings.