O2 Arena

This white dome rising beside the River Thames on the Greenwich Peninsula has one of the most dramatic comeback stories in entertainment history. What began as Britain's most ridiculed public project became one of the world's busiest music venues. The Millennium Dome opened on January 1, 2000, built to celebrate the start of the third millennium. The government spent £789 million creating a massive exhibition space inside this extraordinary structure.

Designers Richard Rogers Partnership embedded time itself into the architecture: the dome stretches 365 meters in diameter, one for each day of the year. It rises 52 meters high, representing the weeks in a year. Twelve yellow masts hold up the fabric roof, symbolizing the months. The exhibition attracted only 6.5 million visitors instead of the expected 12 million. Critics called it a disaster. Politicians debated demolishing it.

The building sat empty, costing taxpayers £1 million per month to maintain. Then in 2007, it reopened as the O2 Arena. Engineers faced an impossible challenge: cranes couldn't operate inside the dome. Their solution was ingenious. They built the 20,000 capacity arena's roof on the ground, then lifted it into position. The arena building was constructed around it.