Birchall, who was with them, Googled images of futuristic buildings, while Foster made more sketches in his notebook. Maybe, Musk suggested, a shard of glass coming out of the lake? The bottom floor could be partly submerged in the water, accessible by a tunnel from another structure on the shore. I later commented that it did not actually seem like a family home. Musk agreed. “It’s more an art project than a house,” he explained. He put off building it.

