In the Christian tradition, the number 666 is described as the "mark of the beast" in the Bible's Book of Revelation. So it was no surprise that Europeans worried as the year 1666 approached. It didn't help that the year before, a plague had wiped out about 100,000 people, a fifth of London's population, leading many to predict the end of times. Then on Sept. 2, 1666, a fire broke out in a bakery on London's Pudding Lane. The fire spread and over three days burned more than 13,000 buildings and destroyed tens of thousands of homes. But in the end, fewer than 10 people perished in the blaze, which, while catastrophic, was not the end of the world.