Japanese traditional architecture, Mokoshi

While the architects of the Japanese castles developed an architectural technique of hiding a floor (e.g. Matsumoto Castle), the builders of the traditional Buddhist constructions developed a style of simulating an extra floor.

This style is called mokoshi, and it means that there's a purely decorative roof located under the real roof. In today's photo, you can see the main hall of Horyu-ji, in Nara, where the lowermost roof is mokoshi.