World expositions are held every five years and are regulated by the General Assembly of the International Exhibitions Bureau (BIE) in Paris. The first "World Expo" was held in 1851 in London, at the Crystal Palace in Hyde Park. Among the most memorable expos to date, special mention must be made of the 1889 Paris exposition and its legacy – the Eiffel Tower, a symbol of the industrial age. In its footsteps Belgium, which hosted the 1958 expo, constructed a landmark to observe the atomic age, the Atomium.
World expositions address topical global themes. All countries of the world are invited to participate and afforded an opportunity to address the general public by tapping into the central theme. Key aims include presenting new ways of attending to the needs of the global civilisation, demonstrating progress in one or more areas of human endeavour, and informing the public about their plans for the future.
The slogan "Feeding the Planet, Energy for Life" reflects the focus on food as the central theme of Expo Milano 2015. Running from 1 May to 31 October 2015, the Expo will host 147 countries, of which 55, among them Slovenia, will have their own pavilions. The event is expected to attract more than 20 million visitors.