My Travels In Peru

The Mystery of Inca Architecture

This chapter is different from all previous ones because it's not about what we saw and did, but about a subject that has puzzled me since we first stepped foot in Peru. How did the Inca build such wonderful stone palaces and temples without the use of steel to cut the stones and the wheel to transport and lift them? As an engineer, I always try to understand not only the what, but also the how? Because of that, I have done a significant amount of research into it. I did the same thing when we visited the pyramids of Giza. Just marvelling at them wasn't sufficient; I also had to understand how the Egyptians did it. Fortunately, there is some information on how the latter were built; and assuming that Incan architects and engineers were equally clever, and there is no reason why they shouldn't have been, then the pyramid construction technology gives us a base to work with.

The Egyptians built large stone pyramids that dwarf the Incan palaces, but archaeologists know with certainty that they had steel tools for cutting stone and the wheel for lifting and transporting them.  Without them, the construction of the pyramids of Giza would have been just as imponderable as the Incan stone edifices.

Actually, Andean big-stone masonry predates the Incas by many centuries. The Tihuanacu, a people who lived during the first millennium, started the trend in what is now western Bolivia. The Incas came along about five centuries after them and copied their technique and style. Moreover, the concept of the cancha, a large open-space or patio surrounded by rectangular buildings, for which the Incas are famous, was actually developed by the Huari, another pre Incan civilization. The Incas were the last great Andean civilization, before the Spanish conquest, and they were prolific builders. Therefore, it's not surprising that all credit is given to them for such marvellous works.

The Incas used a variety of construction methods, ranging from adobe (mud bricks) bonded by mud, loose stones also bonded by mud, and cut stone without mortar. Cut stones were used mostly for temples and palaces for the emperor and the nobility, and were designed to bewilder the common people, and tourists from future generations. The stones were large and perfectly fitted, making the observer wonder how they did it.

In addition to cutting and shaping individual stones to fit perfectly, Inca architects also struck an aesthetically pleasing chord with their design. They combined the massive nature of the buildings with their gently sloping walls and the simple elegance of trapezoidal-shaped doorways, windows, multiple door and window jambs, and niches to inspire admiration and awe. And, all of it was likely achieved with only stone-age technology because copper and bronze tools would not have been very useful for cutting granite blocks. The process for cutting and shaping the stones was probably not much different than that used to make arrowheads. It was stone against stone, slowly chipping away in a labour-intensive process that could only have been speeded up by experienced craftsmen.

Aside from the question of how they cut the blocks to fit so perfectly, another one raises its head, how did they lift them into place? If one person could lift 50 kg, a feat of Olympic champions, it would require 2000 to lift a 100 tonne stone. It's a clear impossibility to get so many people around the stone to lift it! Therefore, leverage must have been used, and lots of it.

Levers remind me of Archimedes's famous expression, "Give me a place to stand, and I shall move the Earth." He was talking about levers, and implied that with one long enough anything could be moved (lifted). When two children sit on each end of a teeter-totter, the beam is balanced and it takes very little effort to make one go up while the other goes down, and vice versa. Changing the location of the fulcrum along the length of the beam allows a small weight to balance a much larger one; and that's leverage!

In Incan construction sites, the lever would have been much higher above the ground, resembling a crane. On one end, the stone to be lifted hung from the beam supported by ropes, and at the other end hung a crate holding a number of small stones to counterbalance the big one to be lifted. Once the lever was balanced, a few people pulling on ropes at the crate-end would lift the big stone into place. At Ollantaytambo and other sites, I saw numerous stones with lifting lugs that workers had not removed, suggesting that ropes had been used to lift them. The specific design of the cranes used by the ancient people of the Andes will never be known, but the concept would have been similar to that described above.

But how did they transport big stones over long distances? It's been assumed that Andean cultures had not discovered and applied the wheel to do useful work. But, is it possible that advanced civilizations capable of building amazing edifices didn't know about the wheel and how to put it to good use? It didn't seem a reasonable assumption to me. The wheel is such a simple concept and every successful civilization had developed it: why not the Andean civilizations?

To my surprise, when we visited Bolivia, we saw a stone wheel with a hole in it. For me, that was a eureka moment. I couldn't restrain my excitement. Everyone in the group thought I had gone nuts. That simple wheel, located outside the Lithic Museum among other stone artefacts found in the Tihuanacu site, told me so clearly what I had believed all along: to transport heavy stones over long distances, Andean people needed the wheel. They didn't make them just so they would end up as museum pieces; they made them because they put them to good use.

The one thing known for certain is that both the Tihuanacans and the Incas had the technology to transport and lift heavy stones. The only uncertainty is about the specifics of the design, not about the concept. The Spaniards should have found such machinery in Ollantaytambo because the city was still a work in progress when they arrived there. But there has been no mention of cranes or wheels in their memoirs. Because of that, archaeologists assumed that the wheel never existed in South America, but id did!

It's unlikely that the stone wheel found in the Tihuanacu site was used for transporting heavy stones, but it clearly shows that the wheel existed in the Andes more than one thousand years ago. Wooden wheels would have been more appropriate for use in transportation, and would have been easy to make by cutting tree trunks into disks. The bronze Andean knives and axes, found extensively in Peruvian and Bolivian museums, would have been more than adequate for the purpose. Thus, they had all the necessary materials: trees to make pulleys and poles for the crane structure; and cotton to make the ropes for pulling. To me, the evidence is pretty compelling!

Once we accept that the wheel was not only known, but also applied to do useful work, transporting heavy stones from the quarries, often located far away from the building sites, becomes a much simpler matter than previously thought. The wheel had been the missing link in solving the mystery, and we found it by chance in Tihuanacu!