Nijō Castle
Japanese castles were designed to be difficult to navigate, with winding routes leading to the inner compound. Blind spots and holes in walls provided constant surveillance of these labyrinthine paths, as exemplified in Himeji Castle. Nijō Castle in Kyoto is constructed with long "nightingale" floors, which rested on metal hinges ("uguisu-bari") specifically designed to squeak loudly when walked over. Grounds covered with gravel also provided early notice of unwanted intruders, and segregated buildings allowed fires to be better contained.