Ninja house

There exist a number of ninja house in classic places for the ninja in Japan, needless to say Iga and Koka.
A ninja house looks like a one-story building when viewed from outside, but it consists of three floors. It indeed has a variety of elaborate designs such as hidden rooms, boltholes, and pitfalls.
The ninja blended gunpowder in a hidden room in the house. The tricks were intended to stop enemy intruders whose aim was to spy on gunpowder recipes, which were the top military secret at that time. Accordingly, the ninja house served as a secret gunpowder laboratory as well as the ninja’s residence.