A national exhibition for the millennium was first proposed in 1994. The idea was dropped when it met with resistance, but it was revived two years later. In 1997 the Labour government of Tony Blair (Blair, Tony) formed the New Millennium Experience Company Ltd. (NMEC), which assumed responsibility for the creation of the dome, the main exhibition, and a series of lesser projects throughout the United Kingdom. Work on the dome began that year.

The foundation, main supports, and Teflon (polytetrafluoroethylene)-coated roof of the dome, which were completed in mid-1998, create an interior floor area of more than 861,000 square feet (80,000 square metres). The roof measures 1,050 feet (320 metres) in diameter, with a total extension of some 969,000 square feet (90,000 square metres), and reaches a maximum height of approximately 165 feet (50 metres). The roof assembly is supported by a web of 2,600 cables suspended from a circle of 12 steel masts, inclined slightly from vertical, that rise nearly 330 feet (100 metres). Designed by architect Sir Richard Rogers, the dome has been both lauded and criticized—although close-up the structure is awe-inspiring, from a distance it resembles a partly flattened mushroom punctured by a circle of 12 pins.

The Millennium Dome has been a controversial project since its inception, owing not only to its enormous cost but also to uncertainties regarding projected attendance rates, the amount and nature of corporate sponsorship, and the educational value of its attractions, which were organized into numerous zones such as Body, Work, Money, Play, Talk, and Rest. The project's supporters noted that skeptics had also attempted to derail Great Britain's two previous world-class exhibitions—the Great Exhibition of 1851, which was housed in the monumental Crystal Palace (a glass-and-iron structure created especially for the occasion), and the Festival of Britain, which opened in 1951 to celebrate (and to help speed along) the country's recovery from World War II. On December 31, 1999, a New Year's Eve celebration at the dome was attended by some 10,500 people, including the prime minister and queen. Opening the next day, the Millennium Dome exhibition lasted until December 31, 2000; however, visitor receipts failed to cover expenses, and the dome was closed to the public. The structure was then sold in December 2001, and in 2007 the renovated building, which included a 20,000-seat auditorium, reopened as The O2; it was named after a mobile phone company.