A team heads out to investigate  the Great Pyramid of Cholula or Tlachihualtepetl (which means man-made mountain), the biggest pyramid in the world with a base four times more massive than that of the Great Pyramid of Giza and almost twice its volume. Interestingly, despite its enormous size, it is frequently mistaken for a mountain.

The  Tlachihualtepetl’s height is around 66 meters or 216 feet, and its width is said to be 450 meters or 1,475 feet. As of now, experts cannot say who is responsible for building the biggest pyramid, but they believe it was created sometime around 300 BCE in honor of the ancient god Quetzalcoatl.

An article in the BBC Future cites that the Spaniards killed 10 percent of natives living in the Aztec city of Cholula in 1519. The city was burnt down to the ground.

The Spanish colonists built the church “Iglesia de Nuestra Señora de los Remediosa” on top of the biggest hill in the city. However, little did they know that the hill was actually the Great Pyramid of Cholula.

Apparently, when the Spanish conquistadors invaded the Americas, the citizens of the city covered the massive monument with soil. The ancient Aztecs used adobe, which is a type of brick made of out of baked mud.

This material can retain moisture, which is conducive to plant life. Over time, the plants thrived in the fertile bricks, taking over the whole structure. The plants and grass covered the pyramid and made it inconvenient for use so the ancient Aztecs had to abandon it.

Now, experts believe that this ancient pyramid is the largest monument ever built. David Carballo, an archaeologist at Boston University, told BBC Future that it must have been abandoned between 7th and 8th century CE. The locals built a newer pyramid-temple close to it but it was also destroyed by the Spaniards.

At 2,300 years after Tlachihualtepetl was built, the site is now a popular destination for tourists, travelers and archaeologists. Further investigations are still needed to uncover the mysteries the pyramid holds.