I know it might not directly be related to politics, but I wonder if it has any significant political meaning? Out of curiousity, I was looking on many cities in North Korea using Google Maps, and I noticed many blue roofs. Any ideas why? Are they military facilities? Living quarters for military and officials?
I'm no expert on Korean culture, but this appears to have been asked many places on the internet already.
Blue tiles appear to be status symbol historically in Korean culture. Insofar as someone can afford blue tiles, they must be wealthy.
This imagery is also present in South Korea; their head of state lives in "the Blue House" which also has these blue tiles. Image from wikimedia:
According to this post, during the 1970's North Korea's government had a modernization effort. As part of this, the government mass purchased construction supplies to be used across the country. It's possible that many of these buildings were constructed at this time and in the same style.