[Photo/China Daily]

Hangzhou Olympic Sports Centre Aquatic Sports Arena

Seating: 6,000

Floor space: 53,959 square meters

Events: Swimming, diving, artistic swimming

Highlights: Together with the Hangzhou Olympic Sports Centre Gymnasium, it is nicknamed the "Turning-into-Butterflies Dual Arena "based on an ancient Chinese folk story that portrays two lovers turning into butterflies in their afterlives.

The building, arguably the biggest of this kind in the world, also looks like two half cocoons. It used 25,000 tons of steel and 3D printing technology to produce each of the more than 20,000 steel components.