It had rained a lot those days, it was a very cold October 1st.
Suddenly some colleagues walked down here to tell me that the rain had carved a crack in front of the Temple of the Feathered Serpent.
Gómez remembers how he hurried down to the Pyramid of the Feathered Serpent.
After some digging, he discovers a shaft that looks like a bottomless well.
When I went down the tunnel I felt fear rise up in me.
It was like losing control.
I still don't understand how I found my courage to go down there, with only a rope tied to my waist and no clue of what was coming.
My heart was beating hard.
I wanted to get out of there.
But then there was the tunnel.
I could see on one side that there was an opening.
Every archaeologist dreams of a moment like this.
Your work is driven by uncertain situations.
Gómez crawls into the crevice.
He can barely see two feet ahead.
As I moved forward I touched the walls.
They were very regular.
And very quickly from the way they felt, I understood: these were not natural walls - they were constructed by human hands.
They were part of an ancient structure.
We can't go further.
Sergio Gómez has reached what appears to be a dead end.
The tunnel is filled with debris.
He wants to know what lies beyond the rubble... and brings in a 3D laser scanner.
Hundreds of thousands of lasers bounce off the tunnel walls back to this device, creating a map of what's ahead.
The 3D image shows the tunnel continuing in a straight path, directly to the Pyramid of the Feathered Serpent which stands at the very center of the city.
The pyramid represents the heart of Teotihuacan, its central landmark.
A tunnel leading directly underneath the Pyramid of the Feathered Serpent must have some significance.
So I came to the conclusion that the tunnel had been sealed to bury something or someone at the end of it directly under the pyramid.
I thought it could be a ruler or a king.