Emperors create impressive structures as tangible proof of their power and control over their kingdom. High nobility often build ceremonial places of worship to win the favor of their creator, raise fortresses to apply pressure to a region physically, or indulge in pleasure palaces where the woes of leadership are massaged away.
Machu Picchu is an Incan citadel, originally constructed by Emperor Pachacuti in 1438 A.D. in the Andes Mountains of Peru, overlooking the Urubamba River valley. It has earned international fame for its sophisticated, earthquake-resistant structures built without mortar, iron tools, or the wheel.
Historians theorize Machu Picchu served all three aforementioned functions, all while remaining completely unknown to the Spanish during the invasion of Latin America. How was that possible?
The nobility never spoke of it
Machu Picchu was a retreat for the aristocracy roughly 80 miles from Cusco, the then-capital of the empire. It's surrounded by steep cliffs and has a single, narrow entrance, enabling a small defense to stave off the attack of an otherwise overwhelming force.
The Spaniards had the reputation of defacing temples and, wherever they met resistance, they employed a scorched-earth policy. So, it's no surprise that the population never spoke of Machu Picchu and kept it a secret; the lower class wasn't allowed to know of its existence either. They went so far as to destroy all roads leading to it, and hid all evidence of their sacred city.
The first rule of Machu Picchu is that you don't talk about Machu Picchu.
The city is earthquake resistant
Machu Picchu sits at 7,972 feet above sea level, and it's peak reaches roughly 8,900 feet. Humans can experience altitude sickness (AMS) at 8,000 feet, but it is uncommon to get AMS unless you come directly from a low-altitude region. Luckily, when building the thing, the Pachacutec Inca brought huge, perfectly cut blocks of stone from rock quarries on site. This prevented them from having to carry the stone blocks up the steep cliffs and allowed them to focus their engineering and achieving seismic-proof buildings without mortar.
The engineer's solution was to cut the blocks into trapezoids that fit perfectly together so that when an earthquake hit, they would fall back into their original place. It also meant that there weren't glaringly obvious supply lines running into the hidden city, making it difficult to find, even during construction.
The population didn't need to leave for fresh water
In 1450, the engineers of Machu Picchu built an aqueduct that ran half a mile from a rain-fed spring to a series of private and public fountains for the population. Two springs fed the canal that satiated the fresh water needs of the people. It measured five by five inches deep at a three percent incline. Using hydraulics, the canal could produce up to 80 gallons per minute.
Machu Picchu's fountains had spouts designed to form a water jet to fill clay water jugs efficiently. These fountains were all interconnected and the residual water was used for agriculture. Naturally, Emperor Pachacuti had the first fountain built directly into his home, allowing the royal family access to the freshest, cleanest water.
Again, not needing to leave to collect water meant there were fewer obvious inroads into the citadel.
Roman technology, worlds removed from Rome
The Inca empire eventually collapsed due to civil war, colonization, and disease transmitted by the Spanish. Machu Picchu itself, however, was never invaded by foreigners and the nobility was spared the fate of the commoners.
"Those who do not learn history are doomed to repeat it." - George Santayana
It begs the question: Would our leaders save us in our darkest hour or would they save themselves in their hidden fortresses?