Photos: DVMG · CC BY 3.0 (1, 4, 5) · ignis · CC BY-SA 3.0 (2, 3)
The Ajikawa Tunnel, completed in 1944, runs under the Aji River between Kujō in Nishi Ward and Nishikujō in Konohana Ward. Cars stopped using it long ago; pedestrians and cyclists still do, going down and up in lifts.
Why it's unique
The Japan Society of Civil Engineers describes it as the only pre-war road tunnel under a river in Japan and the first built by the immersed-tube method. That is a specific, checkable heritage citation.
What you get is not a monument but a working crossing: you use it the way residents do, lift down, walk under the river, lift up.
Before you go
Bicycles go in the lift with you. The car lifts were retired in 1977, and the shafts that once lowered vehicles are part of what makes the entrances look so odd.
Residents report the lifts run roughly 6:00 to midnight, with stairs as the fallback; keep left and push bikes through the passage. It pairs naturally with the Tempozan ferry.
