The Aztecs ruled one of the most powerful civilizations ever seen in the Americas. They were ruthless warriors and ingenious engineers, conquering vast territory with only manpower and building towering pyramids and ambitious civil engineering projects. But after only 200 years, their vast empire was wiped out by Spanish invaders and their cities and monuments were destroyed. Today, many of the secrets of the Aztecs lie buried beneath Mexico City. Now archaeologists are digging deeper than ever to find out who the Aztecs were and how they built their remarkable empire.