On Wednesday, Russia, the United Arab Emirates, Turkey and Brazil will find out whether their chosen cities will host the 2020 World Expo.
Brazil, which is already gearing up to welcome the World Cup next year and the Olympic Games in 2016, has put forward its most populous city Sao Paulo as a candidate.
It is competing with the Turkish city of Izmir, Ekaterinburg in Russia and Dubai in the United Arab Emirates to host the Universal Exposition in 2020, according to the International Exhibitions Bureau (BIE), which oversees the organisation of these large-scale events.
From 0930 GMT on Wednesday, each country will have 20 minutes to showcase their city in a high-pressure contest in Paris, after which the 168 member states of the BIE will vote electronically for their favourite.
"We will know in the evening which of the four countries was chosen," the group said, adding the results would be published on its website.
The World Expo -- which showcases technology, architecture and culture, while drawing visitors to host cities and generating business -- is held every five years.
Shanghai was the last host city and Milan is next in line in 2015.
If Dubai -- home to the world's tallest tower, largest man-made island and one of the world's busiest airports -- is selected, it will be a first for an Arab country.
The glitzy Emirati city has said it would present a "positive" image of tolerance in a region rocked by turmoil.
The bustling metropolis of Sao Paulo, meanwhile, has highlighted its culture of tolerance with communities from all around the world living in the 11-million-strong city.
It has dismissed security concerns following a surge in violence last year.
As for Izmir, a city on Turkey's western coast and known as a centre for medicine, it already bid for a chance to host the 2015 Expo but was rejected for Milan.
Lastly, Russia is presenting the industrial city of Ekaterinburg as part of a bid to develop the Ural region into a hub for technology and innovation, and attract more tourists to this lesser-visited part of the country.