(Please read from the start)
“Further excavations at the Ciudadela were carried out in the 1920s, supervised by Manuel Gamio. Other sections of the site were excavated in the 1940s and 1950s. The first site-wide project of restoration and excavation was carried out by INAH from 1960 to 1965, supervised by Jorge Acosta. This undertaking had the goals of clearing the Avenue of the Dead, consolidating the structures facing it, and excavating the Palace of Quetzalpapalotl.
During the installation of a "sound and light" show in 1971, workers discovered the entrance to a tunnel and cave system underneath the Pyramid of the Sun.[71] Although scholars long thought this to be a natural cave, more recent examinations have established the tunnel was entirely manmade.[72] The interior of the Pyramid of the Sun has never been fully excavated.”
>> Seems there are more secrets there to uncover.
“In 1980-82, another major program of excavation and restoration was carried out at the Pyramid of the Feathered Serpent and the Avenue of the Dead complex. Most recently, a series of excavations at the Pyramid of the Moon have greatly expanded evidence of cultural practices.
Recent discoveries
In late 2003 a tunnel beneath the Temple of the Feathered Serpent was accidentally discovered by Sergio Gómez Chávez and Julie Gazzola, archaeologists of the National Institute of Anthropology and History (INAH). After days of heavy rainstorm Gómez Chávez noticed that a nearly three-foot-wide sinkhole occurred near the foot of the temple pyramid.
First trying to examine the hole with a flashlight from above Gómez could see only darkness, so tied with a line of heavy rope around his waist he was lowered by several colleagues, and descending into the murk he realized it was a perfectly cylindrical shaft. At the bottom he came to rest in apparently ancient construction – a man-made tunnel, blocked in both directions by immense stones. Gómez was aware that archaeologists had previously discovered a narrow tunnel underneath the Pyramid of the Sun, and supposed he was now observing a kind of similar mirror tunnel, leading to a subterranean chamber beneath Temple of the Feathered Serpent. He decided initially to elaborate clear hypothesis and to obtain approval. Meanwhile, he erected a tent over the sinkhole to preserve it from the hundreds of thousands of tourists who visit Teotihuacán. Researchers reported that the tunnel was believed to have been sealed in 200 CE.
Preliminary planning of the exploration and fundraising took more than six years.
Before the start of excavations, beginning in the early months of 2004, Dr. Victor Manuel Velasco Herrera, from UNAM Institute of Geophysics, determined with the help of ground-penetrating radar (GPR) and a team of some 20 archaeologists and workers the approximate length of the tunnel and the presence of internal chambers. They scanned the earth under the Ciudadela, returning every afternoon to upload the results to Gómez’s computers. By 2005, the digital map was complete. The archaeologists explored the tunnel with a remote-controlled robot called Tlaloc II-TC, equipped with an infrared camera and a laser scanner that generates 3D visualization to perform three dimensional register of the spaces beneath the temple. A small opening in the tunnel wall was made and the scanner captured the first images, 37 meters into the passage.
In 2009, the government granted Gómez permission to dig. By the end of 2009 archaeologists of the INAH located the entrance to the tunnel that leads to galleries under the pyramid, where rests of rulers of the ancient city might have been deposited. In August 2010 Gómez Chávez, now director of Tlalocan Project: Underground Road, announced that INAH's investigation of the tunnel – closed nearly 1,800 years ago by Teotihuacan dwellers – will proceed. The INAH team, consisted of about 30 persons supported with national and international advisors at the highest scientific levels, intended to enter the tunnel in September–October 2010. This excavation, the deepest made at the Pre-Hispanic site, was part of the commemorations of the 100th anniversary of archaeological excavations at Teotihuacan and its opening to the public.”
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