And while we're in the Sahara Desert with abundant sunshine, sand and carbon dioxide, let's build a silicon carbide brick factory. Sunlight to provide electrical power and, via focussed mirrors, heat. Sand to supply the silicon. Carbon from carbon dioxide to be extracted from the air at $100 per tonne (well, eventually).

Silicon carbide bricks, emerging gloriously from their tungsten moulds, would possess supreme corrosion resistance and almost double the crushing strength of engineering bricks. High thermal conductivity should reduce cracking and spalling, further increasing lifetime. A short railway journey to the nearest port and water desalination plant whence they can be distributed throughout the world.

We'll beat the Romans! Our public buildings will last for millennia!