Shanghai wants the next World Expo for a number of reasons, not least to try to match rival Beijing's coup of winning the right to stage the 2008 Olympic Games. In recent years, the two cities have played something of a tit-for-tat game in snagging big events and building record-breaking structures. Beijing has the Olympics - the world's largest sporting event - but Shanghai has the world's fastest train and highest hotel, hosted the first motor Grand Prix in China and, in 2010, will become the first Chinese city to host a World Expo, to be held on the banks of the Huangpu River. So what is a World Expo, exactly? In essence, it gives people a chance to see, close up, the technological marvels of the age. During modern times, the surprise and wow factors have diminished somewhat, but in the days before television and the internet, World Expos were hugely popular events that enthralled audiences. The first was in London, in 1851, at the tail-end of the Industrial Revolution. Britain at that time was the world's leading power, with a strong military, a thriving economy, inventive engineers and pioneering scientists. The aim of the extravaganza was to celebrate the nation's achievements - showing its own people, along with any Johnny Foreigner who cared to pop in, that this was a superpower to be reckoned with, destined to dominate for years to come. It was a huge success. The building that housed the event, the Crystal Palace, was a landmark piece of architecture in itself: a structure that used vast glass panes in an age when sturdy stone was the norm. Among the 14,000 items on display were a diamond drill, hydraulic printers, textile machines and a 24-ton block of coal, hewn out of the ground by a mighty, British-designed machine. During the six months it was open, about 6.3 million people filed through the doors. It was clearly a formula that could be repeated elsewhere; the French liked the idea so much they held one of their own in 1855, followed by another four over the next 50 years. One of the world's best known and most loved landmarks, the Eiffel Tower, was constructed for the 1889 World Expo. The simple iron structure was originally intended to be dismantled after the event but proved so popular, it stayed, ultimately becoming a national icon. The most recent World Expo was in Seto City, near Nagoya, allowing Japan to show off its latest hi-tech wizardry. Tickets for Shanghai's expo, themed 'Better City, Better Life', are expected to be snapped up. And the city may well add another record to its list - that for World Expo attendance - when the event finally closes its doors. Organisers anticipate keen interest among the citizens of China's most populous city and the estimated 300 million people who live within a day's drive of the 6.4 sqkm expo site.