At one of the gates of the Himeji castle, there is a cross sign hidden between the regular roof tiles. It is believed that it was put there with the same meaning, as a protective symbol, during the late 16th century, probably by the samurai converted to Christianity who were living in the area.
EXIF info:
Nikon Df
Lens: 24-70mm F/2.8G
Focal Length: 24mm
Aperture: F/7.1
Shutter Speed: 1/1600s
ISO Sensitivity: ISO 400