Nintoku's tomb is the biggest grave in Japan, and by area it ranks among the largest tombs ever built anywhere. It is a keyhole-shaped mound nearly five hundred metres long, ringed by three moats, rising out of the middle of the city of Sakai, and the Imperial Household Agency attributes it to the emperor Nintoku, who is said to have ruled in the fifth century. Archaeologists are less sure about the name, which is why scholars often call it Daisen Kofun, after the neighbourhood. Whatever the truth, the labour that went into it must have been prodigious, with estimates of years of work by thousands of people.
The strange thing is that you cannot really see it. At ground level it looks like a long, wooded park behind water, and the shape that makes it famous only reveals itself from the sky. The best view available to an ordinary visitor is from the free observation lobby on the upper floor of Sakai city hall, which looks across the roofs to the forested hump and its moat. There is also a visitor centre nearby that explains the site, and a path that circles the outer moat in about forty-five minutes of easy walking. Early morning is best, with the water still and the herons fishing.
For a rider the area is easy to reach. The Hanshin expressway runs along the coast from Osaka, and the streets of Sakai are broad and orderly, though busy at rush hour. Parking near the tomb is limited, so check the signs at the visitor centre and be ready to walk. Summer is very hot and humid, with cicadas making a wall of sound in the trees, and the best months are April, May, October and November, when the air is clear and the light is kind.
Fuel is no concern, since Sakai is one of Japan's largest cities and the main roads are lined with stations. For something local, try a kitchen knife shop in the old town, a cup of tea at a Sakai tea room, or a stop at the bicycle museum in the park, which is a small and charming collection and a good place to stay out of the rain.
From here the ride list goes on to Daigo-ji, in Kyoto's south-east hills, a long day's ride through Nara, so start early.