The gate in this photo, Minamimon (the South gate), was the main entrance, dedicated to the domain's lord and to the high-ranking samurai.
EXIF info:
Nikon Df
Lens: VR 28-300mm F/3.5-5.6G
Focal Length: 28mm
Aperture: F/6.3
Shutter Speed: 1/640s
ISO Sensitivity: ISO 200