Aso-san comprises the world's largest caldera—128 km (80 miles) in circumference, from 18 km to 24 km (11 to 15 miles) wide in places—formed after a massive lava-dome collapse some 100,000 years ago. Inside the crater are seven settlements, not to mention herds of cows and horses. The emerald-green grasses that nourish them thrive in the fertile volcanic soil. The crater area, officially named the Aso-Kuju (Mt. Aso National Park), contains five volcanic cones; one is the still-active Naka-dake, which sticks up out of the side of the taller Taka-dake just east of the crater's center. There's no mistaking the sulfurous stench of the mighty belches that gust freely from its mouth.
Looking back on eight decades on making travel history.More