The “nightingale floor” is made with a special timber technique from 17th century which makes it impossible to walk on the floor without it making quite beautiful squeaking sounds.
The idea of the floor surrounding the living and sleeping quarters of the palace was to work as alarm system. No one could enter the space without being heard.
A nightingale (refers to the Japanese Bush Warbler, Uguisu) floor is designed specifically for security reasons. The floorboards of a hallway and the walkboards around a residence are designed to squeak as you walk across it. The nails for the floorboards pass through a metal clip. As you walk on them the floors chirp like a bird (thus the charming name) thereby alerting the residents of the adjacent room of your approach.
Nijo Castle was built in 1603 to be the official Kyoto residence of the first Tokugawa Shogun Ieyasu, and was completed in 1626 by the third Shogun Iemitsu.
A close up of one of the Nightingale floors.
We have had the distinct pleasure of walking over the nightingale floor at Nijo Castle and in Toji-in temple both in Kyoto. Without previous warning we where even more surprised by the experience.
Modifications were completed in 1626, but some of the original castle was destroyed over the years by fire. The main building is Ninomaru Palace that is open for visitors. Taking photos is not allowed inside. There is also a beautiful garden.
[flowplayer src=http://www.zen-garden.org/stream/Nightingale_floor.flv width=480 height=360]
This floor is not vissually different from any floor that we have seen and walked on, without the sound mechanism.
For the full article with more examples and links, see: Nightingale floor, Uguisubari ( 鴬張り ).
Related: Veranda, duckboards and gutter.