The walls of Constantinople worked for hundreds of years until the Turks used cannonballs to blast holes in them. The Wall on the Southern US border is needed to help slowdown or stop drugs, terrorists and other bad things and people.
Babylon had walls. So does Israel. Istanbul. Zimbabwe had a wall and so did Troy. Wiki lists 51 walls. That’s a lot of walls. It’s because they work. America needs one to stop the smuggling along the Mexican border.