The foundations of Fukuoka Castle and part of its moat are all that remains of the original complex. Work is underway to rebuild part of the castle to show what it looked like. The ruins give a good feel for the scale of the original castle though, and form an attractive park. Additionally, you may drop by the Fukuoka Castle Ruins Visitor Center to rent a tablet PC providing an augmented reality visualization of what the castle used to look like as you walk around the park. Visitors who ascend the steps towards the top are rewarded with excellent views of the city, including of the lake in Ohori Park (which in the past used to extend to and surround the castle).

Fukuoka Castle (福岡城, Fukuoka-jō) is a Japanese castle located in Chūō-ku, Fukuoka, Japan. It is also known as Maizuru Castle (舞鶴城 Maizuru-jō) or Seki Castle (石城 Seki-jō). Completed in the early Edo period for tozama daimyō Kuroda Nagamasa, it has been designated a National Historic Site of Japan in 1957.

The castle lies in the centre of Fukuoka, on top of Fukusaki hill. The Naka River (那珂), Naka-gawa in Japanese, acts as a natural moat on the eastern side of the castle, while the western side uses a mudflat as a natural moat. Hakata, a ward with a bustling port, is located on the opposite side of the Naka River to the east. The castle town was established on the northern side, facing the sea.

Much of the castle grounds has been converted to Maizuru Park, which houses several sports facilities, a courthouse, and an art museum. Heiwadai Baseball Stadium, the past home field of the Nishitetsu Lions and the Fukuoka Daiei Hawks, was also located on the castle grounds. Some of the castle's gates as well as its towers and turrets, known as yaguras, are preserved inside the park. The Minamimaru Tamon Yagura (南丸多聞櫓) completed in 1854 is designated as an Important Cultural Property.

The remnants of a korokan (鴻臚館), an ancient guest house for foreign diplomats, were discovered under the castle grounds in 1987, showing that the castle was a vital geographical checkpoint even into the Heian period. This is the only korokan remnant found in all of Japan.