The Shanghai World Expo formally opened its door to the highly avid public Saturday morning.

Top Chinese political advisor Jia Qinglin and International Exhibitions Bureau President Jean-Pierre Lafon activated the opening device together at a commencement ceremony.

The Expo, carrying a theme of "Better City, Better Life", reflects the crystallization of wisdom about urban construction and vision of a better future life, Jia, chairman of the National Committee of the Chinese People's Political Consultative Conference, said while addressing the ceremony.

BIE Secretary Teneral Vicente Gonzalea Loscertales said the Shanghai World Expo would be "the most splendid and unforgettable" and would help the world better understand the present, have a glimpse into the future and strengthen cooperation between countries and organizations.

Visitors, from home and abroad, are thronging to the gates of the Expo park, waiting for security checks in long queues. Around 300,000 tickets have been sold or distributed for the opening day, organizers said.

The Expo is expected to attract 70 million visitors from China and abroad. The park covers an area of 5.28 square kilometers along both sides of the Huangpu River, a tributary of the Yangtze River.