Cities in Russia, Japan and Azerbaijan are about to find out which one of them gets to host the 2025 World Expo, an event expected to draw millions of visitors and showcase the local economy and culture.

The 170 member states of the Paris-based Bureau International des Expositions are voting Friday on whether to award the Expo to Yekaterinburg, Osaka or Baku.

Past world’s fairs brought the world such wonders as the Eiffel Tower, the Ferris Wheel and Seattle’s Space Needle — and today’s version is aimed at finding solutions to challenges facing humanity.

World Expos are held every five years; Milan hosted the last one in 2015, and Dubai in the United Arab Emirates is set to host the next one in 2020 . Cities also hold specialized exhibitions in the interim years. No U.S. city has hosted a world’s fair since the 1980s.

They can last up to six months and cost millions of dollars to host, but can help put a city on the global map by bringing in international visitors and attention.

Yekaterinburg is trying for a second time after an earlier failure to win the expo, and Russian President Vladimir Putin presented the bid Friday via video message — before a Russian singer tried to rev up the crowd with song and dance. This time the Russian city, on the boundary between Europe and Asia in Russia’s Ural Mountains, is promising an expo demonstrating technological innovation and how to balance it with quality of life. Russia’s fourth-largest city, it was one of several Russian sites that hosted World Cup matches this year.

Osaka is pitching itself as the safe, reliable choice — notably because it already held the 1970 Expo, while the other cities are lesser known and would be first-time hosts. It’s proposing an expo on a man-made island on the theme of “Society 5.0” and how to leverage robotics and artificial intelligence for the public good.

Leaders in Osaka, Japan’s third-largest city and the largest in western Japan, are hoping the expo will revitalize a city that has lost much of its luster to Tokyo, the nation’s political and economic capital. They have plans to transform the site into a casino resort after the expo, though there is opposition from residents to bringing casino gambling to town.

Baku has the advantage of having lots of oil money thanks to its Caspian Sea reserves. Its expo would highlight ways to improve human health and redefine human roles in an automating world — and the proposed venue would be designed to evoke the geometry of Azerbaijani carpets. The ex-Soviet, Caspian Sea city of 2.2 million has recently hosted a series of international events, including the Eurovision Song Contest and F1 Grand Prix. It is set to host some UEFA Euro 2020 matches.