The Teotihuacán complex, the ‘city of the gods’, is the most famous pyramid complex in Mexico. The city lies close to Mexico city, and may have been established some hundreds of years before Christ. The large pyramids, the Pyramid of the Sun and the Pyramid of the Moon, would have been built in the first century after Christ. It is not known who built these monuments.

Tunnels run underneath both pyramids, but their function is unclear. For the construction of the pyramids and temples huge quantities of stone and plaster were used, which would have required exceptional production and logistical skills. The plaster and cement used are still of exceptional quality. So why with all this available technology were no houses for ordinary people built, no viaducts, bridges or roads? The construction of such a pyramid lasted dozens of years, and therefore those resposible must have been able to make and to implement construction plans long in advance. Who then were these particularly gifted engineers who set up this impressive construction work, but made no effort for ordinary people?

Until 1905 the Pyramid of the Sun was covered with a 4 meters thick layer of sand. This layer was deliberately deposited on the pyramid before leaving the site for good. The reason of this remains unknown for the time being. During the years after 1905 the layer of sand was removed - by which a thick layer of mica in the pyramid was discovered.