Dating from the beginning of historical memory, the obelisks of ancient Egypt-those tall, tapering shafts typically weighing from 200 to 500 tons-were carved from a single block of solid stone to commemorate the ruler of the moment. If they were still in fashion as monuments, even the ruler of a nation that can lift men to the moon would find it no cinch to erect even a typical Egyptian model. Many of these ancient monoliths, taken from Egypt as trophies...