The O2 is a large entertainment district on the Greenwich peninsula in South East London, England, including an indoor arena, a music club, a Cineworld cinema, an exhibition space, piazzas, bars and restaurants. It was built largely within the former Millennium Dome, a large dome-shaped building built to house an exhibition celebrating the turn of the third millennium; as such, The Dome remains a name in common usage for the venue.
It is often referred by various names: the O2 Dome; the O2 Centre, which properly refers to an unrelated shopping centre on Finchley Road; or The O2 Arena, which properly refers to a smaller indoor arena within The O2. Naming rights to the district were purchased by the mobile telephone provider O2 from its developers, Anschutz Entertainment Group (AEG), during the development of the district. AEG owns the long-term lease on the O2 Arena and surrounding leisure space.