In the 20th century, the walls were symbolic of the confrontation between the two blocks. Despite the fall of the Berlin Wall and the advent of free trade and free movement, they did not disappear.
On the contrary, others appeared with the same security justifications and the same symbolic significance. Since the wall between Israel and Palestinian Territories, the so-called "migratory crises" have been used to justify walls all over the world, from the United States and Mexico, to India and Bangladesh, to Hungary and Romania. Of course, walls are not just physical. Inequalities further divide populations and foster extreme ideologies that lead to fanaticism.