Cosmos Magazine has an article on how maps created by satellites or aircraft are making it easier to reveal details about ancient civilisations:
In 2005 the Internet search company Google launched its virtual globe – Google Earth – constructed from satellite images and aerial photography. The program quickly caught on with millions of users around the world keen to zoom in on their houses, their dream holiday destinations, and even unintentional pictures of boats and planes.
But then, as the story goes, an Italian computer programmer, Luca Mori, turned its use to archaeology. Using Google Earth, he found signs of a Roman villa buried beneath a riverbed. He contacted experts, who decided to excavate.
American archaeologist Scott Madry, Associate Professor at the University of North Carolina at Chapel Hill, stumbled across a newspaper covering Mori's story. Madry had been professionally surveying archaeological sites for more than 25 years, becoming frustrated with the inefficient, dangerous and somewhat inaccurate method of aerial surveying.
Within a few hours on Google Earth, Madry was able to locate 101 features in an area covering 1,440 square kilometres in Central France. These features represented Iron Age, Medieval and Gallo-Roman sites.