Organizers of Shanghai's World Expo have been holding trial runs this week, before the official opening this Saturday, May 1st. About 70 percent of the nearly 200 participants participated in the trials, and visitors were already encountering long lines. Officials now estimate the 6-month event, themed "Better City, Better Life", will attract up to 100 million visitors, 95 percent of them Chinese. Shanghai has spent 400 billion yuan (58.6 billion US dollars) preparing for the Expo, according to state media - more than was spent on the Beijing Olympics. Collected here are photographs of last-minute preparations in Shanghai as they prepare to welcome the world this weekend. ( 37 photos total