Fukuoka Castle (Maizuru-jo) was built in the early Edo period by the Kuroda clan and served as the seat of their domain until the Meiji restoration. Most of the wooden structures were demolished after 1868, and what remains today is a substantial park around the stone walls, some original turrets, and the ruins of the main keep platform that still commands good views over the city and the park below. The cherry blossoms in late March and April make the castle hill one of the best blossom-viewing spots in Fukuoka.
The castle ruins sit within Maizuru Park, which connects seamlessly with Ohori Park to the west. The most intact surviving structure is the Shiomi Yagura turret, a handsome corner tower open for inspection. From the main keep platform the view extends north to Hakata Bay and over the Ohori Park lake. The park and castle grounds are free to enter and well worth a walk. Combined with the Fukuoka Art Museum and a circuit of Ohori Park, the whole area makes a good half-day itinerary.