Washington, DC, has always been a land of constant conflict and battles for supremacy. Thousands of years before it was the nation's capital, the city was patrolled by a predator that looked like a dog, yet was bigger than a grizzly. Tens of millions of years earlier, it endured an asteroid impact that wiped out all life. Earlier still, ferocious meat-eating dinosaurs stalked the suburbs and flying reptiles terrorized the skies over what is now the National Mall.