This multiplex observatory just 2km from North Korea offers prime views into the 'hermit kingdom'. Through binoculars (₩500 for two minutes) you can spy villages, workers in rice fields, military towers and distant mountain ranges. There's a short, introductory video in English, but you'll need to request it to be played.
Bus 26 will get you here, with bus 27 returning to Ganghwa-eup terminal (35 minutes).