Until a revolution or some form of perestrojka, North Korea (officially the Democratic People's Republic of Korea or DPRK) is probably the last country on the face of the planet Earth where you cannot go put up your thumb on the side of the road.
There is a nice North Korea travel documentary called "DPRK: The Land Of Whispers". You can watch it on Youtube.
Guy Delisle wrote a graphic novel about his two months stay in Pyongyang. See Wikipedia page
How to get there
However, you can actually go to North Korea; only independent travel to North Korea is not permitted. As long as you're willing to pay (quite expensive actually) and observe the rules there, you'll be fine and probably in for a treat in the world's most mysterious country.
Country has limited slots for visitors and you can go only on specific important dates and always with an assigned tour agency.
Country has limited slots for visitors but they don't apply on Chinese, Malaysian and Singaporean citizen, who by law, do not need to apply for a North Korean tourist visa, but still subject to the compliance of signing up for a tour to get there. The visa probably costs around 50-70 euros and passport holders of these 2 countries are exempted from paying for it.
You might not be allowed to enter USA after visiting North Korea.
Citizens of South Korea are not permitted to enter North Korea.