The correct answer to this open question is the following.
Spanish explorer Francisco Vázquez Coronado was leading an expedition from México to modern-day Arizona's territory in 1540, trying to find the mysterious cities of Cibola when they found the Grand Canyon and traveled through the Colorado River.
It must have been a wonderful moment of discovery for the Spanish conquerors. To be in front of that majestic sightseeing, speechless, contemplating this nature's wonder never before seen or imagined for them. We could say they were in shock!
Something similar happened to me when I visited the Great City of Teotihuacan, in México. It is an impressive archeological site built by the Teotihucans in central Mexico. The Aztecas found this place abandoned in the 1400s when they were traveling from Aztlán to the Texcoco Lake, where they founded the great city of Tenochtitlan. The capital city of the Aztec Empire.
When I saw the big pyramid of the moon, I was surprised. But when I saw the huge Pyramid of the Sun, I was in shock! It was simply, extraordinary. The architectonic perfection, the symmetry, the proportions, the height. I just wondered how did these people built these magnificent pyramids and temples thousands of years ago, when they did not have the technology we have today.