What secrets do the Inca ruins of Machu Picchu hold?

The ancient city of Machu Picchu is a wonderful architectural masterpiece, located on a mountainside at an altitude of more than 2,300m, like a city floating in the clouds.

Machu Picchu was built over 500 years ago and even in an earthquake-prone area, it still stands. What's more special is that the stones here are stacked so perfectly that it 's impossible to even fit an ATM card between the stones.

This makes people wonder: How did the Incas build such a large-scale city? At that time, people did not have stone carving tools, modern construction machinery, or modern means of transportation, so how could they transport the rocks to the top of the mountain and assemble them accurately?

Machu Picchu is an ancient city built between the Andes Mountains and the Amazon rainforest in Peru. Like a piece of history that was forgotten, it was not until 1911 that Machu Picchu was rediscovered and fortunately, it is still in good condition with many Inca vestiges remaining.

In the past, there was a mysterious country in ancient South America, the Inca Empire that appeared around the 11th century AD. This country was very developed compared to that time and they achieved great achievements in astronomy and history.

However, the Inca Empire is also very mysterious because it was the only major civilization at the time that did not have a written language . Due to the lack of written records, the history of the Inca Empire has always been a mystery to everyone. Much of what we know about the Inca Empire today comes from the records of the Spanish, who invaded the area to plunder and conquer the ancient Inca Empire.

Although this ancient empire has perished, it left behind a mysterious site: Machu Picchu. This city is often called the "Lost City of the Incas" because it was not discovered or destroyed by the Spanish during the Spanish conquest of Peru.

It was not until 1911, when American historian Hiram Bingham was searching for the capital of the Inca Empire, that he discovered the city sleeping on the top of this mountain at an altitude of more than 2,300m.

Archaeological evidence, combined with recent studies of early colonial texts, suggest that Machu Picchu was not a conventional city, but rather a retreat town for the Inca aristocracy. Machu Picchu was designated a UNESCO World Heritage Site in 1983 and a New World Wonder in 2007.

First of all, the Inca construction techniques.  The stones in the entire Machu Picchu ruins, regardless of size, can be placed together tightly. The details of the joints between the stones are so well-processed, it is unbelievable.

The city is said to be able to withstand major earthquakes of magnitude 9 or higher. Given that Peru is located on the Pacific seismic belt and is regularly hit by earthquakes, Machu Picchu has been able to stand at over 2,300 meters for over 500 years, which is enough to demonstrate the exquisite architectural skills of the ancient Incas.

In addition, the arrangement of the stone blocks in Machu Picchu also has its own unique rules . The stones below are relatively large and most of them are irregular in shape. It is said that this arrangement can increase the number of contact surfaces when shaking during an earthquake, thus dispersing the force in different directions and reducing the damage caused by the earthquake.

Inca houses were built of polished stones, fitted together tightly without mortar. As a result, each house was uneven in size and shape.

The foundation of Machu Picchu is one of the important reasons why it can stand tall . The climate here is humid, rainy, and very prone to landslides. To stabilize the mountain, the ancient Incas came up with a way, which is the structure of terraces. 

This design not only solves the drainage problem but also stabilizes the overall structure. The angle of the stone walls is exactly five degrees, which is a stable angle that can transfer most of the weight to the ground. The terraced field structure is divided into three layers, the top layer is fertile soil, the second layer is sand, and the bottom layer is some relatively large gravel and stones.

One advantage of this design is that after it rains, water can quickly seep into the ground instead of running down the hillside, thus avoiding landslides. However, such an engineering feat would have been very difficult for ancient people. How did they do it without measuring tools and specialized knowledge? In addition to the profound design considerations, the manipulation of the stones into various shapes was even more difficult.

The stone blocks in large structures also have a tilt towards each other and are connected to resist earthquakes, thanks to which they have survived to this day, after many historical upheavals.

Experts found that the hardness of these stones is a six on the Mohs scale , while copper and iron are three and four respectively. From this it can be seen that the hardness of copper and iron is not as high as the stone at Machu Picchu, so the carving of the stones here could not have come from iron or copper tools.

So people speculate that the stones at Machu Picchu are the result of hitting stone against stone, but it is clear that stone tools could not have made them so smooth, because the stone would have surely cracked in the process. Therefore, the builders must have used a great deal of skill to shape the stones and make them so smooth.

So, who actually built the entire city? Despite years of exploration and research, very little is known about the history of the city and who built it. At first, it was believed that the city was built by the Inca civilization because of its similar architectural style to that of the Inca civilization, but upon further research, people began to doubt this claim.

First of all, the technical level of the Inca civilization at that time was not enough to build such a large-scale city, and the architectural style here is also very different from that of the Inca civilization. In addition, the way the large stones and small pebbles in the city are stacked on top of each other also shows that the city was likely built by two groups of people.

Getting to Machu Picchu is not a simple journey. There are no buses or trains that go directly from the city.

It is speculated that after the original builders left, the Inca civilization arrived and continued to build. As can be seen from the nearby city of Cusco, after the Spanish conquest in 1532, many new houses were built. But every time there was a major earthquake, their houses would collapse, while the architectural foundations of the city remained unaffected. Even the buildings built by the locals today have been destroyed by earthquakes, and perhaps this is further evidence of the extraordinary construction skills of the city's builders. So who were these extraordinary architects?

Until 2012, someone found a stone gate at Machu Picchu that appeared to have been blocked by later generations. Some experts used metal detectors to investigate and discovered that there was a metal substance in the door, which created a lot of interest.

Some speculate that the secrets of the builders may be buried here, but the Peruvian government has refused to allow anyone to open the door for fear that removing the stones would cause collapse and damage to the entire overall structure of Machu Picchu.

Who built Machu Picchu and how they built it remains a mystery. How could an Inca civilization without writing, the wheel, or iron build such a magical city?