The tunnel was commissioned after Zenkai witnessed villagers falling from the dangerous cliff path known as the 'Chain Ferry' route.
Zenkai funded the project by charging a toll, which is considered one of the earliest recorded bridge or tunnel tolls in Japanese history.
While the original 18th-century section is narrow and rough, sections were widened in the early 20th century to accommodate modern road traffic.
The project was completed with the support of local feudal lords, who eventually provided the necessary funding for the monk's labor.
The site is often associated with the novel 'Enoken no Aonodomon', which popularized the monk's story in Japanese literature.
Aonodōmon is a historic tunnel carved through a sheer rock wall along the Yamakuni River in Nakatsu, Oita. According to local history, the monk Zenkai spent 30 years manually excavating the passage starting in 1730 to provide a safer route for travelers who previously navigated dangerous cliffs. The tunnel features distinct chisel marks visible on the walls, documenting the arduous construction process. It is a key segment of the Yabakei area, a site designated as a Place of Scenic Beauty in Japan. The passage remains open for pedestrian traffic, allowing visitors to walk through the original cavernous sections.
The entrance of the tunnel, which captures the contrast between the dark, hand-hewn interior and the lush greenery of the river gorge.
Walk the full length of the tunnel to see the transition between the original hand-carved stone and modern rock-cut sections.
Visit the nearby Rakan-ji Temple, which shares historical ties to the monks of the Yabakei region.
Wear comfortable, sturdy shoes as the ground surface inside the tunnel can be uneven.
Do not attempt to walk on the narrow road sections if there is high vehicle traffic, as the shoulder space is extremely limited.
Stay within the designated pedestrian walkway; do not climb on or deface the historic rock walls.
