The Shimizu TRY 2004 Mega-City Pyramid is a proposed project for construction of a massive pyramid over Tokyo Bay in Japan. The structure would be 12 times higher than the Great Pyramid at Giza, and would house 750,000 people. If built, it will be the largest man-made structure on Earth. The structure would be 2,004 meters (6,575 feet) high and would answer Tokyo’s increasing lack of space.

The proposed structure is so large that it cannot be built with currently available materials, due to their weight. The design relies on the future availability of super-strong lightweight materials based on carbon nanotubes.

Click here for the Discovery Channel’s Extreme Engineering: City in a Pyramid tour.