World's friendliest/most hostile int'l border

[Michael Z]

With regards to hostile borders, the Joint Security Area aka the North/South Korean border should be very high on any such list. I think it's a testament to the potentially destructive power of ideology that a country based on 5000 years of shared history can suddenly be at war with itself (since, technically, North- and South Korea are still at war with each other; a peace treaty was never signed and both countries have been in a quasi-terminal cease fire since the late 1950s). It's absolutely insane.