Only the capacity for indoor sports, such as basketball, ice hockey, and volleyball, are included.
Venues are only included if they are designed primarily for sports traditionally held indoors.
Venues built for field sports that also host indoor events are not included.
The Caesars Superdome, for example, regularly seats more than 70,000 for basketball games (NCAA and NBA).
By contrast, Saitama Super Arena in the Japanese city of the same name is included because it was built primarily for indoor sports, although it can be configured to host field sports.