No sign, no nothing. I mean, even at the Scottish-English border there's a small sign marking the border crossing.
same at pretty much every US states' borders.
The bit about the Chinese-North Korean border by KillerPollo is wrong. That border is "open" only by comparison with the North Korean-South Korean one. It's probably harder to cross than the US-MExican one. (But thousands of N Koreans slip through every year anyways. Lots of illegal N Korean immigrants in Manchuria.)
I heard the usual route for defectors is to China, then to Japan, then to South Korea.
Which I completely support. ANYTHING to get out of there.
Actually, the usual route out is to China, then dig a cave to live in, then find work as a dishwasher in a restaurant.