Hong Kong, a city of seven million--and growing fast. By the year 2050 Hong Kong's population will almost double. Where will these people live? There's only one place to go--up. Fast forward 50 years.This is the tallest man-made structure on the planet. Its name:Millennium Tower. It would stand twice as tall as anything built before. Over 60 thousand people would live or work here. Millennium's designers think it represents the best solution for the coming population explosion. It would cost ten billion dollars and consume more building materials than any single nation could produce. David Nelson, one of Millennium's key designers, said:"It would be a massive project and a world project. But to actually realize it, resources would have to come from all over the globe. The challenge and the motivation for doing it would be to realize one of the world's largest and most complex construction projects." Millennium would be more complex than anything ever built. So its builders won't know for sure the building is safe until it's up, and they can't afford to make an error. Massive earthquakes have brought down entire cities in this part of the world. Can Millennium's designers make it immune to these quakes of the earth? For Millennium, like all the other buildings, safety is just one concern among many. It will need to be a home, one that welcomes people in. Getting people into the building and making sure they have a great experience well be what makes Millennium successful, but how to do it? For the design team, the secret was to bring all the elements of city life within. Cafes and restaurants, theatres and stores would provide entertainment. Health clubs, even schools and medical clinics would also serve the towers' residents. Millennium's designers have proven something. Things that seem impossible today, might just become reality tomorrow. The engineering problems have, for the most part, already been solved. Our achievements are limited only by our imaginations. The success of Millennium mainly relies on   _  .
how many resources will be used how many nations will work together whether people can enjoy their life in it whether it is safe for people to live in