Scattered across the vast blue expanse of the Pacific Ocean lie two of the ancient world’s most bewildering construction achievements. On a remote Micronesian island, a city of nearly 100 artificial ...

Alien megastructures are a fun idea, but they seem likely to collapse under the weight of their ambition. Vast machines that wrap around stars, encase entire planets, or even have the ability to push ...

Add Yahoo as a preferred source to see more of our stories on Google. (cokada/iStock/Getty Images) Alien megastructures built to harvest stellar energy or alter the orbits of stars may be physically ...