City Hall Station is the closest station to Nagoya Castle. When you exit the station from Exit 7, which is the closest exit, you'll find a gate that doesn't look like a subway exit at all.
You'll find wooden benches right outside the exit.
While you can't see the castle keep from here, you can get a glimpse of the stone walls of Nagoya Castle.

City Hall Station is the closest station to Nagoya Castle. When you exit the station from Exit 7, which is the closest exit, you'll find a gate that doesn't look like a subway exit at all.
You'll find wooden benches right outside the exit.
While you can't see the castle keep from here, you can get a glimpse of the stone walls of Nagoya Castle.