(CHEN FEI)

Visitors walk along the Expo Axis to pavilions of the World Expo in Shanghai on the first day of the event's trial run on April 20.

The Expo, with the theme of "Better City, Better Life," will run from May 1 to October 31. More than 240 countries and international organizations will participate. It is expected to attract more than 70 million visitors from around the world.

The Expo Axis is the central passage at the Expo site. It consists of steel-glass funnels with a 1,000-meter-long membrane structure and is the main entrance and exit of the Expo.