The temporary London attraction built for the millennium celebrations on the Greenwich Peninsula was the Millennium Dome.
The Millennium Dome opened to the public on January 1, 2000, as the centerpiece of the United Kingdom's millennium celebrations. Its enormous circular roof, supported by distinctive masts and cables, covered a large exhibition space beside the River Thames in southeast London.
Inside, visitors encountered themed zones and displays exploring subjects such as the human body, science, communication, and the future. The project attracted millions of visitors during its first year but also faced criticism over its cost, management, and the visitor experience.
The building was later renamed The O2 after redevelopment and became a major venue for concerts, sports, and entertainment. The name “Millennium Dome” therefore usually refers to the original exhibition and the building's 2000-era identity, while “The O2” describes its later commercial use.