What we know about ancient civilizations comes from what those civilizations left behind. Sometimes it's a shard of pottery, part of a tool, a piece of jewelry. Archaeologists scour the earth for such remnants of ancient civilizations to piece together a picture of the past. But in Egypt there are clues to the past that are hard to miss: they're six and a half million tons, taller than the Statue of Liberty, and as wide as 10 football fields. You don't need a trowel and a brush to discover these artifacts; you can see them from space!