Sazaedo

Sazaedo was built in 1796 on the slope of Iimoriyama and is one of the strangest surviving wooden structures in Japan. Inside, two helical ramps wind through the sixteen-metre tower, one ascending and one descending, connected only at the top - a double helix in timber, so that a pilgrim walking up never crosses the path of one walking down. The point was practical: the building held images of the thirty-three Kannon of the Saigoku pilgrimage, and the one-way spiral let a crowd complete the circuit in order without congestion. It is the earliest known application of the double-helix idea in a building anywhere, and it is a designated important cultural property. The name means turban shell, for the spiral. The interior is bare boards and pilgrim stickers now; the images were removed in the nineteenth century.

What you actually see

• A timber double helix - separate up and down ramps meeting only at the top.
• A one-way pilgrim circuit - designed so a crowd never crosses itself.
• 1796 construction - the earliest known building use of the double-helix form.
• Bare interior - boards and old pilgrim stickers; the images were removed long ago.

When to go

All year. An hour, including the hill.

Honest expectations

It is small and takes fifteen minutes inside. The ramps are steep and the floorboards uneven. The hill approach is a long stair unless you pay for the escalator. The surrounding site is heavily commercialised.

Nearby

Tsuruga Castle is south-west; Aizu-Wakamatsu is below the hill.