Hakata Port Tower is a practical little viewpoint rather than a skyline icon. Its observation room looks over Hakata Bay, the ferry terminals, port cranes, and the city edge, giving Fukuoka a maritime frame that is easy to miss from Tenjin or Hakata Station.
The tower is most worthwhile if you are already near Bayside Place, waiting for a ferry, or interested in the working harbor. It is a short visit, but the free view and the port setting make it a useful counterpoint to Fukuoka's shopping streets and food stalls.