Built on the side of a mountain, facing the waterfall Nachi-no-taki, this shrine is one of Kii's most spiritual places, a site of ancient nature worship and one of the Kumano Sanzan (three great shrines of Kumano). The deity worshipped here is the waterfall itself, believed to be a kami. After visiting the shrine, walk down to the falls.
It's a 30-minute walk up 467 stairs from the nearest bus stop (Nachi-san) to the shrine. Get more atmosphere (and exercise) by starting at Daimon-zaka, the official approach (with another 267 steps), lined with cedar trees. At the entrance to Daimon-zaka are two particularly tall and sturdy trees nicknamed meoto-sugi ('married-couple cedars'); it's naturally a popular photo spot.