Kuragari Tsuro
The Kuragari Tsuro (“dark passage”) is a 7-meter-wide T-shaped underground passage that runs beneath the Honmaru Goten Palace. The longer leg runs 82 meters east to west and the shorter leg runs 44 meters north to south. The passageway has thick stone walls bonded with mortar to keep out rainwater. A staircase midway along the east-west leg of the passage leads up to the main hall area of the Honmaru Goten Palace above.
While the palace is a partial reproduction dating from 2005, the stone base, of which this passage is a part, is original. The gorgeously decorated tatami rooms in the palace above were mainly used by the daimyo for official meetings and ceremonies; they were not living spaces.