Remarkably—with just three months until opening day—construction on the Expo grounds is nearing completion. And, says AS+GG founding partner Gordon Gill, the contractors “have fought really hard for the integrity of our design and have maintained the quality of the architecture.”

The Chicago-based firm, which is also working on the world’s tallest tower, in Jeddah, Saudi Arabia, beat out more than 100 firms in a 2013 open international competition, with a short list that included designs by Zaha Hadid, Snøhetta, UNStudio, and other offices.

AS+GG was given a parcel nearly 62-acres for the Expo, just outside downtown Astana, situated within a larger 433-acre site. One of the main challenges was to buffer the buildings from the steppe’s extreme climate. The architects also needed to embrace the sustainable theme by incorporating renewable energy sources. Crucially, the architects also considered the life of the project post Expo.

“We wondered what was going on with the rest of the 433-acre site,” says Gill. “So we designed a two-phase legacy master plan for the city, as opposed to designing an Expo that would be used for only 13 weeks.”

From above, the AS+GG-planned Expo site appears as a wheel, with pathways radiating from a central spherical structure. This 260-foot-diameter glass sphere proved to be one of the most technically challenging elements of AS+GG’s design, due to its complex grid-shell structure and large double-curved, insulated glass panels. The sphere also relies on technologies such as photovoltaics and wind turbines, and has a geothermal system to supplement heating and cooling.

Whereas past expositions have focused on stand-alone national pavilions (like Milan in 2015), this year’s fairgrounds will feature four “neighborhoods” to accommodate up to 120 nations’ pavilions. These four wedge-shaped neighborhoods circle the central sphere in a horseshoe array. The first phase also includes extensive parkland, a 3,000-seat auditorium, a hotel, housing, and retail space. Phase II will convert the grounds into an extension of Astana itself, with office space in the former exhibition halls, and developer-led mixed-use parcels, complete with housing and schools.

In spite of the promising progress, the architects’ enthusiasm is tempered by caution. From construction photos and a recent site visit, the plan seems “primarily intact” says Gill, “but we don’t know everything.” The architects intend to return to Astana this spring for a final walkthrough.

“Walking through it is a humbling experience,” says Gill. “Everywhere you turn, you can see something you did, and you want to make sure it’s working together. Right now, I think we’re in pretty good shape.”