The Millennium Dome, originally built to celebrate the start of the new millennium, was a massive dome-shaped building in London that housed a year-long exhibition in 2000. Despite high expectations and political significance, the project fell short of its predicted visitor numbers and faced financial and management challenges. The Dome's unique design, featuring a large white canopy supported by yellow towers, made it a recognizable landmark in the UK. After the exhibition, the Dome was repurposed into The O2 Arena, becoming a popular entertainment venue in London. There are some free options but also many tickets and events which you need to pay for.