With almost two years to go until the Tokyo 2020 Olympics, the Japan Sport Council opened up the construction site of the main stadium to the press on Wednesday and revealed a nearly-half completed structure.

The stadium, located in Tokyo's central Shinjuku Ward, is about 40 percent complete with construction "going smoothly" according to the JSC. Construction of the stadium began in December 2016 and is now entering the second half of its planned 36-month term.

Costs are expected to reach nearly 150 billion yen (about $1.3 billion) to build the 68,000-seat venue, which will be able to hold about 80,000 people with temporary seating.

Upon completion next November, the venue will become the new National Stadium and officially replace the old stadium used for the 1964 Tokyo Olympics. It will host the opening and closing ceremonies as well as athletics events and football matches.

One of the showpieces of the stadium, designed by Japanese architect Kengo Kuma, is a roof made from Japanese wood.

Scheduled to be completed next May, it will cover spectator seating and is considered to be the most difficult aspect of construction. About 60 meters of the roof on the upper part of the east side of seating has been finished so far.

In order to mitigate the humid conditions during the country's summer months, the stadium was designed to allow wind to pass through from outside and will have about 180 fans. Devices that spray a cool mist will also be installed over the entrance gates.

The stadium project was shrouded in controversy in its early stages. Construction work began about 14 months later than planned, after the original design by the late Iraqi-British architect Zaha Hadid was discarded following public outcry over the spiraling cost.

The new National Stadium was also supposed to host games during the 2019 Rugby World Cup in Japan, including the final, but the delay made it impossible. Tokyo's Ajinomoto Stadium will now host Rugby World Cup games, with the final being staged in Yokohama.