The Games are scheduled to run until Aug. 8. The Paralympics are scheduled to take place Aug. 24 to Sept. 5.
Here's a look at the Games:
- This is the second time the Olympics has been held in Tokyo, which previously hosted the Games in 1964. The 1972 and 1998 Winter Games were also hosted by Japan, in Sapporo and Nagano, respectively.
- Invitations to the games were sent to countries, states and territories represented by 206 national Olympic committees and to the Refugee Olympic Team.
- Tokyo's new National Stadium was designed by architect Kengo Kuma following high-profile criticism and spiraling costs of the original plans.
- Kuma sourced more than 70,000 cubic feet of timber from each of the country's 47 prefectures for the stadium. "We wanted to create something that captures the people's thoughts on the environment or the Earth at the time," Kuma told CNN in an interview in June 2019.
- Athletes competing in the Games will sleep on bed frames made of cardboard and mattresses made of plastic to reduce the event's carbon footprint, according to organizers.