text: History Following the closure of the Millennium Experience at the end of 2000, the Millennium Dome was leased to Meridian Delta Ltd. in December 2001, for redevelopment as an entertainment complex. This included plans for an indoor arena.
  Construction of the arena started in 2003, and finished in 2007. In December 2004, after the interior of the dome had been largely cleared and before building work inside began, the dome was used as the main venue for the annual Crisis Open Christmas organised by the London-based homelessness charity Crisis.
  Owing to the impossibility of using cranes inside the dome structure, the arena's roof was constructed on the ground within the dome and then lifted; the arena building's structure was then built around the roof. The arena building, which houses the arena and the arena concourse, is independent from all other buildings in the O2 and houses all the arena's facilities. The arena building itself takes up 40% of the total dome structure.
  The seating arrangement throughout the whole arena can be modified, similar to the AO Arena in Manchester. The ground surface can also be changed between ice rink, basketball court, exhibition space, conference venue, private hire venue and concert venue.
  The arena was designed to reduce echoing, a problem common among older arenas used for concerts.