The Mega-City Pyramid is a project which aims at constructing a massive pyramid over Tokyo Bay in Japan. It is proposed to build the structure 2,004 meters high and house 750,000 people thus making it the largest man-made structure.

Perimeter of the foundation above ground would be 2,000 meters. Area of the foundation would be 8 square km. Infrastructure is an area of approximately 25 square km. Gross building area is about 88 square km of facilities.
 
Layers 1 to 4: residential, offices, etc.
Layers 5 to 8: research, leisure, etc. The height of each layer is 250.5 m (for 8 layers, the pyramid is 2,004 m tall). The pyramid structure would be composed of 55 smaller pyramids stacked five high.

 
Challenges

The proposed structure requires lightweight materials based on carbon nanotubes for its initiation as it cannot be built with present available materials due to their weight.