The most amazing thing about the Berlin Wall is that the world didn't see it coming.
It's easy to dismiss this as hindsight bias. But at least one man - the brilliant German classical liberal Eugen Richter - saw the Wall coming over sixty years before it went up. In 1891, decades and revolutions before Orwell's Animal Farm, Richter published Pictures of the Socialist Future. It's a dystopian novel about what happens to Germany after a socialist takeover.
I just finished reading the aforementioned book; it's available as a free PDF here; it really is astounding that Richter, in 1891, was able to foresee so accurately and well. Via The Writing on the Wall, Bryan Caplan | EconLog | Library of Economics and Liberty.