Focusing on the future of energy, this year's Expo opened on Saturday in Astana, Kazakhstan, and runs through Sept. 10. During its three-month run, the Expo is expected to host 2 million visitors to the nearly 1.3 million square feet of exhibition space and cultural pavilions. The 2/3-square-mile master plan, designed by Chicago-based Adrian Smith + Gordon Gill Architecture (AS+GG), also includes retail, hospitality, office, cultural, civic, and residential zones. AS+GG's master plan also includes legacy plans for post-Expo use.

At the center of the Expo complex is the "Nur Alem," which the Expo website describes as the "the world's largest spherical building." The 53,820-square-foot base houses the host country's pavilion, and the 262-foot-wide sphere contains the Museum of Future Energy and a floor detailing the future of the host city. The complex also includes the 1,000-seat Astana Energy Hall, the Astana Congress Center, and the Astana Art Center—all designed by AS+GG.

In a piece published on Friday, the day before the opening, Forbes contributor Kenneth Rapoza described the complex this way: "The $3 billion Expo pavilion looks like a re-make of Disney's Epcot Center. There's a large glass globe in the middle that serves as Kazakhstan's country showcase. Then surrounding the globe in a semi-circle are country pavilions. The U.S. is near The Vatican and Poland. At 11,000 square feet, it's half the size of China's. The rest of the site, or the other semi-circle around the globe, is a mix of open space and an arts center."

The structures will house the Astana International Financial Center after the Expo wraps, according to Rapoza. On the firm's website, AS+GG note: "When completed, the legacy development will be one of the most sustainably built in the world."