Northern Air Temple

Built on a mountain high above the clouds, the Northern Air Temple is practically in a world of its own. Long ago it was the home to airbending monks, as well as the championship for Air Bison Poling. But time and war caused the Air Nomad's disappearance, though new people - refugees from a flood, eventually found it many decades later. Building upon what they found, an inventor "upgraded" the temple with pipelines pumping hot air and made many inventions, including hang-gliders inspired by the temple paintings. But these upgrades destroyed the historical remains of the Air Nomad society. Not to mention the utter desecration of building Fire Nation weapons inside the temple's sanctuary room... Horrible.