The O2 Arena, commonly known as the O2, is a multi-purpose indoor arena in the centre of The O2 entertainment complex on the Greenwich Peninsula in southeast London. It opened in its present form in 2007. It has the second-highest seating capacity of any indoor venue in the United Kingdom, behind the Manchester Arena, and in 2008 was the world's busiest music arena. As of 2022, it is the ninth-largest building in the world by volume. The arena was built under the Millennium Dome (renamed The O2), a large dome-shaped building built to house an exhibition celebrating the turn of the third millennium; as the structure still stands over the arena, The Dome remains a name in common usage for the venue. The arena, as well as the overall The O2 complex, is named after its primary sponsor, the telecommunications company O2, a subsidiary of Virgin Media O2. 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 Manchester Arena. 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. On 18 February 2022 during Storm Eunice, large sections of the arena's fabric roof were shredded, causing the evacuation of 1,000 people, and the venue to close. It was later announced that repair works would take place