Hirosaki Castle was completed in 1611 for the Tsugaru clan. The surviving three-storey keep is modest in size, but the wider park is superb: moats, gates, corner turrets, stone walls, and thousands of cherry trees that make spring the city's peak season.
The castle tower serves as a small museum, but the grounds are the real draw. Allow time to loop the moats and bridges, especially if the blossoms are out.