North Korea is practically a mythical place by US standards.
Only a very select few are allowed across its borders, and then, the rules of conduct prohibit visitors from placing even one toe off the beaten path. You'll need nearly endless documentation, endless patience, and you better be on your best behavior.
But should you jump through the hoops, a day in Pyongyang or Rason could be one of the most memorable of your life. You'll get a window into one of the most cut-off cultures in the world — and a fresh look into your own. But until then, read up and dream.