The abandoned city of Teotihuacan has fascinated Mexicans and archaeologists alike for centuries - but the majority of its treasures have only come to light recently and are now on show for the first time in Europe. Teotihuacan, founded in around 200 BC, is home to the world's third largest pyramid and an enduring historical mystery - no one knows who established the city, which at its peak had 200,000 inhabitants, or how it came to be abandoned by 700 AD.
It is a central part of Mexican history and identity, said Gereon Sievernich, director of the Martin-Gropius-Bau in the German capital Berlin, which is hosting an exhibition titled Teotihuacan: Mexico's Mysterious Pyramid City until October 1.
"It was discovered twice so to speak," he said. "First by the Aztecs, who settled in Mexico and built up the great state that was later conquered by the Spanish. Teotihuacan is an Aztec word. It means 'created by the Gods' or something along those lines."
The second "discovery" came when Mexico wrenched its independence from Spain. While searching to establish its new national identity, Mexico spent a lot of time and money investigating Teotihuacan, which lies around 50 kilometres north of Mexico City, Sievernich said. "It's as important to the Mexicans as the Egyptian pyramids are to the Egyptians," he said.
And the timing of the German exhibition is no coincidence. "Mexico is celebrating 200 years of independence this year, and the 100th anniversary of the beginning of their revolution," Sievernich said. "Germany is also celebrating 20 years of reunification this year, so that was the political motivation and a good reason for the Mexicans to allow such valuable national treasures abroad," he added.
Most of these treasures are relatively "new" - and, therefore, all the more sensational - because the most intensive excavation work was done in the last 30 years. Tunnelling under the Pyramid of the Moon and under buildings at the southern end of the site - at its height the city covered 20 square kilometres - archaeologists found human remains along with brightly coloured wall paintings, stone sculptures, jewellery, intricately designed human figurines, elaborate clay pots and incense burners that had been astonishingly well preserved.
There are necklaces of jade, seashells and human teeth, arrowheads and knives made of obsidian, a type of sharp rock produced in volcanic explosions. One figurine of a woman has moving limbs and others have compartments in the middle, which open up to reveal delicately wrought scenes, possibly from the lives of the people with whom they were buried.
The richly decorated containers show bloody scenes of ritual sacrifice, decorated warriors and priests carrying out fertility rites. There is even a remarkably modern looking container in the shape of a "crazy chicken." From studying the wall paintings, dominated by red and green colours, archaeologists believe that the city had four rulers. "A sort of quadrumvirate," Sievernich said, ruling over a central American empire with enormous regional influence.
"London was much smaller then, Berlin didn't even exist," he noted. Teotihuacan is believed to have had a well-trained army, since it managed to keep a hold on such a large empire. The design and layout of the pyramids also show that its citizens had mathematical knowledge and observed the patterns of the sun and the moon.
"Archaeologists also found corals and sea shells from 2,000 kilometres away, so you can assume they had extensive links, whether through trade or otherwise," Sievernich said. Other discoveries point to darker traditions. "Through the finds we've learnt that they practised human sacrifice, though not on people from the city. They were probably prisoners," Sievernich said.
But despite the recent advances at the Teotihuacan archaeological site, which was made a UNESCO heritage site in 1987, historians are not much closer to identifying the people who founded it. "There are no written records, nothing," Sievernich said. "We found some symbols in wall paintings which could be a similar to the Mayan symbol language, but we don't know how to decode it."
And its end in the seventh century remains equally mysterious. Large parts of the city where burned, but whether this was as a result of invasion or internal uprising is unclear. A small number of people remained in the city for 100 years, but later abandoned it. But Sievernich is confident that more can be learned. "It's one of the most wonderful and adventuresome archeological sites in the world today," he said. "We could keep digging there for 200 years and still wouldn't have found all its secrets."