Nijō Castle
In Japanese architecture there is a type of floor known as "uguisubari", which is generally translated into English as "nightingale floor". These floors have squeaking floorboards that resemble the Japanese bush warbler's low chirping, and are meant to be so designed to warn sleepers of the approach of ninja. Examples can be seen at Eikan-dō temple, Nijō Castle and Chion-in temple in Kyoto.