This ancient Incan city is hidden amidst the lush greenery and the towering peaks of the Andes Mountains. It isn’t just a collection of ruins; it’s a testament to the ingenuity and brilliance of an ancient civilization. And it has captured the imaginations of people around the world.

Here’s a cool fact about the discovery of this lost city—the place probably would never have been discovered without the help of a kid just like you. You see, after two years of research to pinpoint the location of the “Lost City of the Incas” and raise money for his expedition, intrepid American historian and explorer Hiram Bingham set off into the Peruvian jungle in 1911 with nothing more than an educated guess as to where it might be. He eventually only found the spot with the aid of an 11-year-old Quechua Indian boy.

Upon discovering the site, Bingham wondered, “What could this place be?” A century later, we still don’t know why they constructed this place on a spot that practically touches the sky. Nobody is quite sure when Machu Picchu was first built—educated guesses put it at around 1450—or why it was abandoned a century later. Researchers still aren’t sure what its original function might have been—a place of worship, a royal estate, an astronomical observatory? And nobody can say with any certainty what became of its original inhabitants.

The Inca were the end result of 5,000 years of a civilization that started at the same time as Egypt and Mesopotamia. Because of conquest and disease, however, they were only around for 100 years. But they left behind this undisturbed site that is just incredible.

About a third of the ruins have been reconstructed. And it’s easy to imagine how the city must have looked in Inca times, clinging to the top of an emerald green mountain ridge in the rain forest. The site comprises a main plaza—flanked by stone homes, temples, workshops, bathing areas, and a royal palace, surrounded by stone terraces where maize and other crops were grown. Estimates put the population at no more than 1,000 at any given time. Although the reconstructed temples are the most impressive buildings, Machu Picchu’s most important structure is the Intihuatana or “hitching post of the sun,” a mysterious abstract stone construction that ancient priests may have used to study the heavens and make astrological predictions.

At the Temple of the Condor, you can see how the large stone in the middle of the structure has been carved to resemble the head and neck feathers of a huge Andean bird, and how the rocks behind are shaped into outspread condor wings. And gazing down on the Temple of the Sun, you can see the Serpent Window, which, according to legend, was used to admit snakes to the shrine.

Even without knowing the background, cosmology (cosmology is the study of the origin and development of the universe), or history of the Inca and Machu Picchu, it is incredibly impressive. The more you observe and see, the more you wonder about it. How did these people do this? And why?

Machu Picchu was built on two fault lines, so it is no stranger to earthquakes. When one occurs, the stones bounce like they are dancing and then fall back into place. It is because of this engineering feat that the site still stands today.

Some more interesting facts about the place. More than a hundred skeletons were found at the site. Today, we now know that they were close to evenly split between women and men.

Hiram Bingham thought he had discovered the Lost City of Vilcabamba, even though we now know it was Machu Picchu. Unbeknownst to him, he had also traveled through Vilcabamba in 1911.

Machu Picchu is built on a mountain ridge that is 7,970 feet high (2,430 meters). 5,280 feet equals one mile. So, Machu Picchu is almost 1 and one-half miles high. Think how long it would take you to hike all the way to the top of that mountain ridge since it is almost straight up in the air. That’s a lot of climbing to do.

AIME