Fukuoka Castle Ruins
The Fukuoka Castle Ruins spread over a large area that is currently used as a park in downtown Fukuoka. There are several areas to see, including the Tamon turret (pictured left), the various gardens and orchards, and some stone structures. I was unfortunate to miss the best two seasons here: spring and autumn. The ruins are a popular area for viewing cherry blossoms. The cherry orchard is located below the stone ruins next to the Maizuru park running track. There are also several other fruit orchards and gardens to stroll through. If you walk to the top of the ruins, you can get a good 360 view of the park.
The ruins are located right next to Ohori park, so you can take in both sites without too much travel.