(01 of16)
Open Image ModalView of the temple of the Feathered Serpent at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(02 of16)
Open Image ModalPartial view of the temple of the Feathered Serpent at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(03 of16)
Open Image ModalA robot called "Tlaloque 1" is shown to the press during a press conference at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on November 10, 2010. "Tlaloque 1" will help in the investigation of a tunnel found this year under the ruins of the temple of the feathered serpent at the archaeological site. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(04 of16)
Open Image ModalA robot called "Tlaloque 1" is shown to the press during a press conference at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on November 10, 2010. "Tlaloque 1" will help in the investigation of a tunnel found this year under the ruins of the temple of the feathered serpent at the archaeological site. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(05 of16)
Open Image ModalA robot called "Tlaloque 1" is shown to the press during a press conference at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on November 10, 2010. "Tlaloque 1" will help in the investigation of a tunnel found this year under the ruins of the temple of the feathered serpent at the archaeological site. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(06 of16)
Open Image ModalA robot called "Tlaloque 1" is shown to the press during a press conference at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on November 10, 2010. "Tlaloque 1" will help in the investigation of a tunnel found this year under the ruins of the temple of the feathered serpent at the archaeological site. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(07 of16)
Open Image ModalSkilled workers search for archaelogical pieces among remains from an excavation at the temple of the Feathered Serpent at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
Mvd152047(08 of16)
Open Image ModalSkilled workers search for archaelogical pieces among remains from an excavation at the temple of the Feathered Serpent at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(09 of16)
Open Image ModalSkilled workers search for archaelogical pieces among remains from an excavation at the temple of the Feathered Serpent at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(10 of16)
Open Image ModalSkilled workers search for archaelogical pieces among remains from an excavation at the temple of the Feathered Serpent at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(11 of16)
Open Image ModalPartial view of the temple of the Feathered Serpent at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(12 of16)
Open Image ModalMexican archaeologist Sergio Gomez gives some explanations inside a tunnel found under the ruins of the Feathered Serpent temple at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(13 of16)
Open Image ModalArchaeologists work inside a tunnel found under the ruins of the Feathered Serpent temple at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(14 of16)
Open Image ModalArchaeologists work inside a tunnel found under the ruins of the Feathered Serpent temple at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(15 of16)
Open Image ModalArchaeologists work inside a tunnel found under the ruins of the Feathered Serpent temple at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)
(16 of16)
Open Image ModalArchaeologists work inside a tunnel found under the ruins of the Feathered Serpent temple at the archaeological site of Teotihuacan, 45 km northeast of Mexico City, on March 24, 2011. Archeologists are unearthing a 2,000-year-old tunnel outside bustling modern day Mexico City searching for clues to one of the region's most influential former civilizations. Heavy rains at the site of Teotihuacan, accidentally provided the first sign of the tunnel's existence in 2003, when the water made a tiny hole in the ground. AFP PHOTO/Ronaldo Schemidt (Photo credit should read Ronaldo Schemidt/AFP/Getty Images)