I still don't think it's close to enough. At 170km long, 200m wide, 500m tall, the volume is 17,000,000,000 m^3. They're planning on spending just $29.41 per

I still don't think it's close to enough. At 170km long, 200m wide, 500m tall, the volume is 17,000,000,000 m^3. They're planning on spending just $29.41 per m^3. Just trying to get a point of reference, the Burj Rafal is 308m tall with a 20,000 m^2 plot and cost $320M. Running the numbers they spent $520/m^3 on that, and it's shorter (I presume added height increases costs and complexity). Infrastructure was also likely already provided by the city, and not counted in that budget. Honestly, I think even material costs are at least an order of magnitude higher than they want. The scope of this boggles the mind. They need 170M m^2 of mirrored glass just to cover the outside of this. That's not even touching the foundation and reinforcement it takes to support a 170km long, 500m tall wall that's going to bear all the force of wind coming off the ocean. Wind speeds seem to peak at about 16m/s, so the force on a 1m section of the wall would be ~78 kN. That's roughly the force of 3 Tesla Model S' at full acceleration (but spread vertically). The force across the entire wall would be equal to ~381 Saturn V rockets at lift-off, or about 23 times the force that sunlight exerts on the entire Earth.