Daisen Kofun — Emperor Nintoku's Keyhole Tomb (5th Century)

**Keyhole tomb significance:** Kofun (古墳, 'old tomb') period (250–538 CE) saw construction of massive keyhole-shaped burial mounds for emperors and nobility. The keyhole shape (round rear section connected to trapezoidal front section) is unique to Japan and symbolizes connection between divine realm (circle) and earthly realm (square). Daisen Kofun's scale (486m length) surpasses Great Pyramid of Giza by area (though much shorter at 35m height). **Ground-level limitations:** The tomb's scale is impossible to perceive from ground level — walking the perimeter (2.8km circumference) feels like walking next to a forested hill with moats. The keyhole shape is only visible from aerial views. The Sakai City Hall observation deck (4km away) provides distant overview but detail is lost. For true appreciation, view aerial photos/videos before visiting to mentally visualize what you're walking around. **Kofun cycling route:** Sakai City has 100+ kofun burial mounds concentrated in the Mozu area. Rent a bicycle at Mozu Station (¥300/day) and follow the Kofun Cycling Road (10km route) passing 20+ kofun of various sizes. The route includes Richu Kofun (365m), Nisanzai Kofun (300m), and small kofun accessible on foot. Allocate half-day for full kofun cycling experience.