My hyperbolic suggestion was to build four pyramids of carbon cubes. They'd have to be about 5km wide and similarly tall, and would be by far the largest struct

My hyperbolic suggestion was to build four pyramids of carbon cubes. They'd have to be about 5km wide and similarly tall, and would be by far the largest structures ever built by humanity. You'd need supplemental oxygen to spend any substantial time on the peak. Assuming we had too-cheap-to-meter fusion or a dyson swarm or something like that, of course. Call it total cost of say, $50 trillion, no big deal, right?