With ecological issues like global warming and overpopulation on the rise, Hollywood’s apocalyptic dystopias—think Waterworld or Children of Men—may be closer than we anticipate. Focusing on self-sufficiency and sustainability, architects around the world are redefining structural design, visualizing entire cities in the clouds, underground and out at sea.

Check out these innovative projects, including a “mega pyramid” and “super tower” to learn what our architectural future may hold.

The 10 Most Insane Architectural Projects Proposed Right Now.