The five cities made their submissions on Monday last week. Each of the BIE's 161 member states receives a copy of the dossiers, which will be examined in detail by its executive committee in May next year, then by the general assembly in July. A decision will be announced shortly afterwards.
The following is a rundown of the cities and countries bidding. Jonathan Gornall reports.
Population about 80,000
Famous for Ayutthaya Historical Park, site of ruins of the former capital of the Kingdom of Siam, destroyed by the Burmese in 1767 and now a 290-hectare UN World Heritage site
Expo theme"Redefine globalisation, balanced life, sustainable living"
Proposed dates January 15 to June 15, 2020
What they say "Ayutthaya, the former capital city, is a diplomatic crossroad that opened the door to Asian civilisation, a port city, a centre of trade, the Venice of the East, linking the Silk Road to the world. Ayutthaya is really a city of perfect balance - a perfect illustration of our proposed theme, Redefine globalisation: balanced life, sustainable living." - Akapol Sorasuchart, President of the Thailand Convention & Exhibition Bureau
Thailand country file
Size 513,120 square kilometres (51st in world, twice the size of US state of Wyoming)
Population 67.05 million (19th)
Life expectancy 73.83 years (114th)
GDP per capita $9,400 (Dh34,525, 114th)
By per-capita GDP, Thailand is the poorest of the five countries in the running, a factor which could work in its favour. Encouraging progress is one of the central values of the BIE, which believes Expos "foster education through experience [and] development through innovation". Staging an Expo, it says, can be a "powerful catalyst for growth" in the host country. But political unrest could work against the city's bid. Last Saturday, trouble flared again after the government announced that former prime minister Abhisit Vejjajiva would be charged with murder. The charge relates to the violent clampdown on the wave of anti-government protests that swept the country in 2010, leaving 90 dead and more than 1,000 injured. The city of Ayutthaya, 85 kilometres from the capital, Bangkok, is an interesting choice for a bid centred on the redefinition of globalisation. As the capital of Siam from the 14th to the 18th century, the city was once a bustling trade crossroads and the place at which Thailand first made contact with the rest of the world. As such, says the bid, it is the "perfect location from which Thailand can once again open its doors to the world, and a stage where every nation can showcase their strengths and share their ideas". However, the fact that Thailand recently hosted Royal Flora Ratchaphruek 2006, an international horticultural exposition recognised by the BIE, might make it difficult for the organisation to grant the country a second international show so soon.
Population 2 million
Famous for Signature building projects, from Burj Al Arab and the Palm Jumeirah island, to Burj Khalifa, the world's tallest building
Expo theme "Connecting minds, creating the future"
Proposed dates January 1 to June 30, 2020
What they say "Dubai is ideally placed to host the world on the occasion of the 2020 World Expo. We would be able to do it. We would be honoured to do it." - Sheikh Mohammed bin Rashid, Vice President and the Ruler of Dubai
UAE country file
Size 83,600 sq km (115th in world, slightly smaller than US state of Maine)
Population 7.9 million (116th)
Life expectancy 76.71 years (72nd)
GDP per capita $47,700 (12th)
In many ways Dubai is a natural fit for the ethos of the world expo and, says Urso Chappell, founder of ExpoBids.com, "definitely one of the serious candidates" for 2020. Multicultural exchange, says the BIE, "is the foundation of each Expo and shared action is their engine". Connecting people, as Dubai's impressive bid highlights, "lies at the heart of the UAE's vision as a cosmopolitan nation … by connecting minds, our common aspirations are celebrated and together we can work to create a brighter future". The UAE is by far the smallest of the bidding countries but the wealthiest in per-capita GDP - $47,700 compared with the nearest rival, Russia, at $16,700. If Dubai were to win it would be staging the Expo on the eve of the UAE's 50th anniversary celebrations. One measure of how far the nation has come in the four decades since unification is that it is already the most advanced of the bidders in terms of life expectancy. But perhaps the most crucial factor in the bid's favour is that an Expo in Dubai would be the first to be staged in the Middle East, not to mention the North Africa and South Asia region. With the city's rapid pace of development over the past few decades and its record of hosting world-class events and conferences, nobody could doubt Dubai is one of the best-placed candidates to realise its bold vision - the development of a 438-hectare site at Dubai Trade Centre Jebel Ali, halfway between the city and Abu Dhabi. As its bid proclaims, Dubai is "logistically ready to host a World Expo". Ideally placed as a global travel centre, within an eight-hour flight of 80 per cent of the world's population, the city would doubtless attract large numbers of visitors, which is a crucial factor for the BIE. By 2015, Dubai International Airport is expected to be the busiest in the world and the new Al Maktoum Airport, next to the proposed Expo site, will be able to handle 160 million passengers a year.
Population 1.35 million
Famous for The Tsar and his family were murdered here by the Bolsheviks in 1918
Expo theme "The global mind"
Proposed dates May 1 to October 31, 2020
What they say "Ekaterinburg Expo 2020 shall be an excellent opportunity to demonstrate innovatively, technologically and scientifically advanced Russia engaging foreign partners to a mutual conversation on issues mentioned." - Denis Manturov, acting minister of industry and trade of the Russian Federation
Russia country file
Size 17.09 million sq km (1st in world, 1.8 times size of US)
Population 142.5 million (9th)
Life expectancy 66.46 years (164th)
GDP per capita $16,700 (72nd)
Ekaterinburg, Russia's fourth-largest city, is 1,430km east of Moscow, roughly on the dividing line between Europe and Asia. If successful, it would be the first Expo hosted by Russia. More important, perhaps, the bid makes a case for opening up to the world the vast and lesser-known tracts of the country in and beyond the Ural Mountains. It is possible to detect a political tinge to the city's plan, which could play well to the BIE's concern for human rights. The ambitious objective, says the city, is "to engage the world in an open dialogue about our shared future and help to enhance the transformation of Russia towards a more open and expressive society". Less convincing is its theme, The Global Mind, the mission of which reads almost like a parody of some of the more touchy-feely BIE-friendly babble adopted by some of the more over-eager expo organisers. It will "survey world opinion through seven universal questions with the goal of communicating the values, hopes, dreams and aspirations of people from every culture and nation across the world in a single discussion".
Population 2.78 million
Famous for Formerly known as Smyrna, rebuilt by Alexander the Great
Expo theme "New routes to a better world, health for all"
Proposed dates April 30 to October 31, 2020
What they say "The theme, which includes the healthy-living concept, is based on a very strong content to catch attention and global participation. For the first time at the East of the Mediterranean, this Expo organisation is very important for us because it will strengthen peace and raise life expectancy of the people living in this area." - Aziz Kocaoglu, mayor of Izmir
Turkey country file
Size 783,562 sq km (37th in world, slightly bigger than US state of Texas)
Population 75.7 million (17th)
Life expectancy 72.77 years (125th)
GDP per capita $14,400 (88th)
Izmir is probably Dubai's most serious rival to host Expo 2020. As a winner, either country would be the first Islamic state to host an Expo. The city's bid has, of course, the usual all-embracing ambition - "to provide a meeting place for all mankind in harmony with all regions and cultures, and help to establish the basis for a better and healthier world" - but could easily attract the sympathy vote. Izmir was in the running to host Expo 2015, a race it lost by a narrow margin to Milan, and had dusted itself off to try again, doubtless having learnt much from its experience. It would also be the first to host an Expo in the eastern Mediterranean. As "the most western point of the East, and the most eastern point of the West", as its bid puts it, it is and has been for many centuries "a unique intercultural bridge between countries".
Sao Paulo, Brazil
Population 11.31 million
Famous for Financial capital of Brazil, 10th richest city in the world
Theme "Power of diversity, harmony for growth"
Proposed dates May 15 to November 15, 2020
What they say "In the upcoming years, we are going to host the World Cup and the Olympic Games. In 2020, Brazil and Sao Paulo will be well prepared for hosting this big event. All levels of government will work together to honour this tradition of great shows." - Michel Temer, vice president of Brazil
Brazil country file
Size 8.51 million sq km (5th in world, slightly smaller than US)
Population 194 million
Life expectancy 72.79 years (124th)
GDP per capita $11,800 (102nd)
Sao Paulo has a long record of hosting major events but, although the Expo would be the nation's first to be sanctioned by the BIE, Brazil's looming embarrassment of world-class event riches could work against the bid.
Expo 2020 will be staged after Brazil's 2014 football World Cup and 2016 summer Olympics. Nevertheless, Sao Paulo is certainly going for it, planning a 502-hectare exhibition site with hotels, malls and a major conference centre, and new roads, railways, airport and "digital highway" infrastructure. But it will be hard for the city to convince the BIE that it needs the economic boost traditionally provided when an Expo comes to town. The world's 10th wealthiest city, it is the engine of Brazil's growth. That, presumably, is why in their bid the organisers can do no better than suggest that the Expo would be an opportunity only to "consolidate" Sao Paulo's "leadership role in the internationalisation of the Brazilian economy and to become a continental crossroad for people and trade".