<p> On This Spot? </p> <p> See buildings soar and traffic zoom, a kaleidoscope of color and movement. Now turn the page and time-travel back 175 years, where on the same spot carriages bumped and pigs raced across cobblestones. Turn again and go back 400 years to when a Lenape Indian trail crossed the spot. Now travel farther still, to when glaciers crept . . . dinosaurs preyed . . . a tropical sea teemed with ancient creatures . . . back 540 million years, when rock was all you could see. </p> <p> What happened on this spot? What will happen next? Look out your window. What happened on that spot? </p>