Centuries-old temples in Japan have an ingenious way of keeping intruders from breaking in and stealing their prized treasures — floors that actually sing like birds.
Designed to make a chirping sound when walked upon with the most silent steps, the type of flooring system is called Nightingale floors, or uguisubari, which literally means “bush warbler bird guard watch” in Japan.
The system, developed to keep spies, thieves, and assassins from sneaking in undetected, is said to be so effective that even the stealthiest ninjas might trigger the sound.
Commonly found in the hallways of palaces and temples, the chirping floors are constructed from dried boards designed in a way that the flooring nails rub against a metal jacket or clamp, creating the sound.
Most notable examples include the Nijo Castle, temples Chion-in, Eikan-dō Zenrin-ji and Daikaku-ji, which are all located in Kyoto.
According to SoraNews24, the buildings designate a certain rhythm for residents or security team to follow when walking on the floors to tell if the chirping sound is being generated by the steps of a friend or foe.
If they hear the nightingale floors start singing an unfamiliar tune, the building’s guards are immediately alerted to foil the intruder’s attempt.
Since it is also able to detect the intruder’s location by the loudness of the sound and the direction where it is coming from, the nightingale flooring system made for an effective early warning security device back in the day.
Quite impressively, these structures built centuries ago still function perfectly today. Watch some examples of people fooling around with the nightingale floors below: