Nijō Castle
"" are floors that make a chirping sound when walked upon. These floors were used in the hallways of some temples and palaces, the most famous example being Nijō Castle, in Kyoto, Japan. Dry boards naturally creak under pressure, but these floors were built in a way that the flooring nails rub against a jacket or clamp, causing chirping noises. It is unclear if the design was intentional. It seems that, at least initially, the effect arose by chance. An information sign in Nijō castle states that "The singing sound is not actually intentional, stemming rather from the movement of nails against clumps in the floor caused by wear and tear over the years". Legend has it that the squeaking floors were used as a security device, assuring that none could sneak through the corridors undetected.