If the road to hell is paved with good intentions, then giant border walls must be made of the same material. For the cost, these fixed national fortifications did little good in keeping out those meant to stay on the other side.
Even the Night's Watch didn't see it coming.
Historically, most barrier fortifications fall well short of its designer's expectations and these were no different: they were just the most famous ones.
1. The Great Wall of China
This series of walls and forts was actually contructed over many centuries, beginning in the third century, BCE. The Chinese originally wanted to keep out roving barbarians from the North while protecting that border from invasion. It did neither.
And Superman wasn't around to rebuild it with his Wall Rebuilding... Vision. (Yes, someone put this in a movie.)
Originally conceived to be 3,000 miles long and anywhere from 15 to 50 high, it was the largest construction project by any civilization ever. Eventually, the Chinese expanded well beyond the wall. And even when they had to retreat, they were still overrun by the Liao and Jin people...and later, by the Great Khan.
2. The Theodosian Walls of Constantinople
These walls were also a series of fortifications built around the furthest extent of Constantinople (now Istanbul) by Emperor Theodosius II between 412-414 CE. While the three miles long, 40-foot walls were effective at keeping out medieval attackers, they weren't so good against the new cannon technology.
And once inside... well... you know.
The walls of the city fell in 1453, breached by the Ottoman Turks after only 53 days. The Byzantine defenders knew about the technology but spurned the inventor of the siege cannon because they couldn't afford it. He then turned around and sold it to the Ottoman Sultan.
3. The Siegfried Line
This monster fortification featured concrete walls and ceilings anywhere from 20 inches to five feet thick. It had thousands of bunkers and tens of thousands of pillboxes and tank traps. Much of the 390 mile stretch of wall, concrete, razor wire, and mines must have been a very formidable sight, after its construction between 1938 and 1940.
That's why we don't use earthworks so much anymore.
Armed with 100 water cannons, the Egyptians broke through the $300 million fortification in about two hours. The water cannons swept away the earthworks and a 53-minute artillery barrage breached other, reinforced areas of the wall.