Today, as President Trump builds the US-Mexico border wall, there are over 77 border barriers (walls or fences) around the globe. Many of them were erected after September 11, 2001. The number when the Berlin wall fell in 1989 was 15, and 7 after WWII. Despite the exploding number of border walls, constructing border walls is not a recent idea. Border walls have been commonly used for various purposes over history.

One of the oldest and longest border walls is the Great Wall of China. The materials of the wall are mainly stone and brick. The first part of the wall was built just after China unified for the first time in about 221 BCE, more than 2000 years ago. The primary purpose of the wall is to ward off enemies for the north, especially Xiongnu (the ancestors of Huns). With this wall, ancient China gained a strategical advantage in wars. The wall not only blocked enemies but also provided the Chinese army an ideal position to observe the approaching enemies.   

The Great Wall is not the only ancient border wall. In Europe, Roman Emperor Hadrian commissioned the Hadrian Wall. The wall is located in Britain. It marked the northwest frontier of the Roman Empire, establishing the terrestrial sovereignty of the empire. The construction started at about 122 AD and took nearly six years to complete. The majority is made of stone, but some portions are fabricated from the turf. In the Roman Empire, the number of soldiers was limited, which posed a difficulty for the government to control such a grand empire. By building the Hadrian Wall, the empire needed fewer soldiers for frontier control. Therefore, more soldiers could work to maintain domestic stability rather than distracted by neighboring states’ invasions.   

The Greco-Roman world paved the way for medieval fortifications, which became increasingly complex. When Emperor Constantine I moved the Roman capital to the port town of Byzantium in 324 AD, he decided to construct the Walls of Constantinople. The materials are rubbles, limestone, and bricks. The scale of these walls is unprecedented. More importantly, the walls effectively integrate man-made barriers with natural obstacles. After the construction of the walls, the entire city was enclosed, reinforced by hundreds of bastions and towers. The wall guarded the Byzantine Empire for over a thousand years before it was broken down by cannon in the 15th century.

Transforming into the modern era, people found it more difficult to cross the border walls. For example, Berlin Wall, created during the Cold War to separate East and West Germany, consisted of concrete blocked topped by barbered wires. Plus, strong police forces enhanced border control. More than 140 people were killed when trying to cross the Berlin Wall in the 1960s. The major aim of the USSR is to prevent people from West Germany from entering the socialist state. Aside from warding off western people, the wall also blocked the flowing of western ideas into East Germany. All East Germany people lived under the propagandas of the USSR, without knowing anything about the outside world.

In recent years, the rise of populism leads to anti-immigrants trends around the globe. For example, President Trump attempts to construct the US-Mexico border wall to stop illegal immigrants from Mexico. In this case, some people propose a digital border wall. A “digital wall” is a row of in-ground cameras, infrared sensors, and motion detectors. Instead of actively preventing illicit border crossing, the wall alerts human security teams to take action. The digital wall would be cheaper and more sustainable than a traditional border wall. With advanced surveillance techniques, this type of border wall is highly likely to prevail in the future. 

As we can see, from warding off enemies to preventing illegal immigrants, border walls have been symbols of exclusion. The form of the walls also changes as our technology improves—from stones and concretes to a “virtual wall” today. But we should stop to think for a moment: Are all these walls necessary? The border walls, aside from limiting people’s movements, symbolize the barrier of two cultures. At a time of globalization, it is cultural diffusion and viewpoint exchanges that fascinate the growth of our world. Thus, these walls would slow down our development by stopping cultural interactions. For our generation, we should break down the “walls” (both physically and metaphorically) and build bridges instead.