Here’s a fun flooring fact for building geeks: a type of flooring called ‘nightingale’ or uguisu-bari uses a special structure to make noise when an unknowing intruder walks across it, warning of their presence. They got their nickname because they seem to ‘sing’ in response to pressure when the mechanism is activated. Developed in Japan to guard treasures against approaching ninjas, the most famous example of uguisu-bari can be seen in Kyoto’s Nijo Castle.
The mechanism intentionally places planks of wood atop a framework of supporting beams loosely enough to enable a bit of play. When even a tiny amount of pressure is applied, flooring nails rub against a jacket or clamp, creating chirping noises that sound like little birds.
In fact, the quieter people try to walk, the louder the sounds. The floors are pretty complex, and not everyone could afford them, so they’re most often found in seats of power, and are still in use today.
The joints look like upside-down V-shapes when spotted under the Nijo Castle walkway, which was built during the Edo period in 1679. It’s said that when a commander visited the castle, bodyguards would be stationed in hidden doorways, waiting for signs of potential trouble. Guards and allies learned a special way of walking on them in a set rhythm so they weren’t mistaken for intruders.