Age of Miracles Author:John Brunner When suddenly all the fissionable material on Earth was exploded, Earthmen had their first notice of the aliens' arrival. — And by the time the panic, death and chaos had been sorted out, reports were coming in about mysterious cities scattered across the face of the planet - huge areas of flickering light and awesome free energy, disorienting to... more » human senses and impregnable to attack.
The question was: were they alien bases or something else?« less