This article presents an analysis of the Great Wall of China and the Berlin Wall which reveals that both grew from unique political, historical, geographical, cultural, and economic circumstances. The purpose of this article is to provide new arguments for a debate that all too often has been waged with emotions, polemics, and misinformation. The idea for this article evolved from discussions with colleagues and students who have asked the author on his opinion on the Berlin Wall and the proposed United States/Mexico border fence. This article could be useful for a variety of teaching activities in World History and United States History survey courses. It provides a starting point for evaluating the arguments for and against the wall under construction across the southwestern United States. It offers a basis for demonstrating how knowledge of the past and a historical perspective are invaluable for formulating questions about the present and making a whole range of political, economic, and cultural decisions. Furthermore, the article provides a set of case studies for asking questions about the self-perception of civilizations and how they chose to defend themselves from internal and external threats. (Contains 56 notes.)