From smart cities to bridges you can run marathons on, these giant infrastructure projects will define the future.
The world is full of unfathomably huge projects happening right under our noses.
Take the Hong Kong-Zhuhai-Macau Bridge, which will link three major Chinese cities in the country's quest to bring 42 million people together. Or Norway's plan to build the world's first fully-submerged floating tunnel to cut travel times between fjords in half.
Those efforts and many others illustrate how investing billions of dollars in enormous projects can collectively make the world a better place to live.
Here are some of the biggest projects the world has seen so far.