Get off the Meijo line at Shiyakusho station and you’re underneath the boulevard beside which Nagoya City Hall stands. Nagoya Castle is diagonally across the boulevard from Nagoya City Hall, hence this castle plan designed on stairs in the metro station.
… as well as the obligatory shachihoko.
This corridor directly connects the metro station with the basement floor of the city hall.
… which looks like this from above the ground.
It looked like this less than a century ago.