This is a very cool UNESCO site not to far from my stomping grounds. Funnily enough it took me 18 years to visit it. I should have gone sooner! What an amazing village. I immediately felt transported back in time as I wandered around the houses and the snow.
I could try to explain more about the houses and their origin but wikipedia does a pretty decent job of it. I've included some links.
About the village - http://en.wikipedia.org/wiki/Shirakawa,_Gifu_(village)
About the houses - http://en.wikipedia.org/wiki/Minka
Japan tourism site - http://www.jnto.go.jp/eng/location/regional/gifu/sirakawagou.html