>> parcak: a lot.can't keep track. >> whitaker: parcak has found more than 3,000 ancient settlements in egypt; roman sites across europe and north africa; viking sites in iceland. >> parcak: so, we're going to look up here. >> whitaker: one of her early important finds was in a farm field near the ancient roman city of portus. it's a site in italy where archaeologists have been digging for a decade, but hadn't been able to find the city's amphitheater-- until sarah parcak looked at the satellite photos. >> parcak: what you see in this image are-- fields. but you can't really see much of anything. >> whitaker: not much. >> parcak: so we can go to the next image. so, if you see a circle right here-- and what you're looking at is the likely amphitheater of portus. it's in that field. >> whitaker: how 'bout that! and from the surface, you would see nothing? >> parcak: absolutely nothing, walking over the top of it. >> whitaker: so your satellite sensors are not peering through the ground? >> parcak: uh-uh,