It was called Valeriana. Between 750 and 850 AD it was inhabited by about 50,000 people. Graduate student Luke Old-Thomas discovered the city almost by accident. He found the results of a lidar survey on Google with a map of the sites underground. After processing the data using archaeological methods, he saw an ancient city with pyramids, sports arenas and amphitheaters that simply no one had noticed before. In terms of size, Valeriana is second only to the largest Mayan city, Calakmul, with an area of more than 13 thousand km².