Keyhole-shaped tumuli are scattered throughout the city of Sakai in Japan's Osaka Prefecture. A tumulus is a mound of earth or stone raised over a grave, and the largest one shown in this Overview is the final resting place of Emperor Nintoku. Nearly 1,600 feet (486 m) long with a mound 115 feet (35 m) high, it covers the largest area of any tomb in the world.34°33'45.2"N, 135°29'11.1"E