Civilizations desk
Sacsayhuamán: who built the walls above Cusco, and how?
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Four named Inca architects, a carbon date from the 1100s, and a glassy sheen some researchers say no chisel made. The walls above Cusco still hold more than one story.
Sacsayhuaman is the megalithic complex on the hill above Cusco, Peru, and the record credits its great zigzag walls to the Inca from the mid-15th century, built over an earlier Killke phase. Alternative researchers argue that the finest fitted stones are far older and show heat-glazed surfaces. Peru protects the site as Cultural Heritage of the Nation.
Key takeaways
- An Inca chronicler names four architects of the fortress and dates its start to Pachacutec or his son.
- A Peruvian archaeologist said in 2008 that carbon dating placed an earlier Killke construction phase in the 1100s.
- Researchers Jan Peter de Jong and Christopher Jordan argue that glassy spots on Cusco-area stones are a heat-made glaze, citing a lab analysis of one sample.
- Most of the fortress was pulled down after the conquest and its stones reused in colonial Cusco.
- Peru declared the site Cultural Heritage of the Nation under Law 23765.
Who really raised the walls of Sacsayhuamán (also spelled Sacsayhuaman, or Saqsaywaman)? On the hill above Cusco, polygonal blocks taller than a person lock together in three zigzag tiers [1]. The standard answer is the Inca. Some archaeologists add an earlier people beneath them, and a line of independent researchers argues for a much older age with a technique nobody has explained. Here is each case in the words of the people who make it, from our ancient civilizations desk.
Who built Sacsayhuamán, according to the record?
The oldest detailed account comes from Garcilaso de la Vega, who played in the ruins as a boy in Cusco and later wrote his Royal Commentaries of the Incas [3]. He writes that the Inca Ynca Yupanqui began the fortress, "although some would have it that it was begun by his father Pachacutec," who left a plan and a model [3]. He names four chief architects: Huallpa Rimachi, Maricanchi, Acahuana and Calla Cunchuy [3].
World History Encyclopedia follows that account. It dates the start to the mid-15th century under Pachacuti or his son Thupa Inca Yupanqui, and says 20,000 laborers were drafted under the Inca system of tribute labor [1].
The Inca may not have been first, though. In 2008, archaeologists working at the edge of the fortress reported a temple with Inca and pre-Inca phases [4]. Peruvian archaeologist Luis Lumbreras told The Associated Press that earlier carbon-14 dating showed the Killke culture built the fortress in the 1100s, and said the finds confirm "the aggregate nature of the fortress" [4]. The encyclopedia, by contrast, says pottery finds point to earlier occupation by Inca residents [1]. The two readings have not been reconciled in print.
Why do people call Sacsayhuamán a mystery?
The sense of mystery is not modern. Garcilaso reports a priest who wondered whether the stones could have been placed "without the aid of the devil," and he records that the work was "put down to enchantment" [3]. His own verdict:
But it cannot be conceived how these Indians, without proper engines or tools, could work, dress, raise and lower enormous rocks (which are more like pieces of a mountain than the stones of an edifice), and fix them so accurately in their places.
Modern alternative researchers push that doubt further. Author and tour leader Brien Foerster argues that the original builders lived thousands of years before the Inca [7]:
The precision of the stone work in some cases could not have been achieved using the Inca bronze tools.
The strongest version of the case, with a lab result attached, comes from Jan Peter de Jong, Christopher Jordan and Jesús Gamarra, son of the Peruvian researcher Alfredo Gamarra. It sits in the dossier below, beside what the excavators answer.
What is the case for a lost technique at Sacsayhuamán?
The vitrification argument
In a 2011 paper, Jan Peter de Jong and Christopher Jordan argue that shiny, smooth, discolored patches on stones at Sacsayhuamán and other Cusco-area sites are glaze made by heat, not polish [5]. They say the patches often sit on the edges where the stones join, and that a flashlight test at night shows light refracting and splitting through a surface layer, as at the rock called the Inca Throne [5]. They credit the Peruvian Alfredo Gamarra with first identifying the effect, and say Erich von Däniken brought it to popular attention in the 1970s [5].
Their evidence is one sample. They had a smooth layer from Tetecaca, a worked cave above Cusco, analyzed at the University of Utrecht with a microprobe [5]. The body of the rock read as limestone. The surface was dominated by silicon, with more aluminum and magnesium, which they say shows "a material was added to the surface of the stone" [5]. They compare it to ancient ceramic glazes and conclude:
The results strongly indicate that heat was used to produce the surface, which raises several questions.
They are open about the limits. They write that, to their knowledge, no scientific tests had been made on the stones themselves, that the glassy state of the layer still needs electron microscopy, and that how such heat could be produced is unknown [5].
The three ages
De Jong also sets out Alfredo Gamarra's wider theory [6]. Gamarra saw three building styles at every site around Cusco and read them as three periods. In the first two, he held, gravity and density were lower, so stone could be shaped and moved on a grander scale. The second period is the age of perfectly fitted, mortarless blocks, and de Jong names the walls of Sacsayhuamán as a prime example [6]. The third and simplest style, small hammer-dressed stones, is in his account "in most cases the work of the Inca" [6]. De Jong says Gamarra reached these readings through dreams, literature, fieldwork and study of Quechua and Aymara [6].
Softened stone
A popular story holds that the Inca softened stone with a plant extract. De Jong himself rejects it: he calls it impossible at that scale and asks where such a plant would be [6].
What do archaeologists and the chroniclers answer?
The mainstream reading rests on tool marks and unfinished work. World History Encyclopedia says blocks were shaped with harder stones and bronze tools, mostly by pounding, roughed out at quarries and finished on site, as abandoned blocks on the routes show [1]. Ropes, logs, levers and earthen ramps moved them, and some still carry grip nodes [1]. Grinding stones and sand gave the final surface [1]. Experimental archaeology, it adds, showed that dressing the stones was much quicker than scholars had assumed [1].
Garcilaso adds a detail the "no mortar" legend skips. Of the wall facing the city, he writes that the builders "used for mortar a mixture of red clay, which is very sticky" to fill the small gaps [3]. He also records Inca histories of more than twenty thousand people hauling a single great stone with cables [3].
On scale, the encyclopedia gives many blocks over 4 meters tall and over 100 tons, in three terraces whose walls zigzag for more than 540 meters [1].
Neither side has published the test that would settle the glaze question: chemical analysis of the joint surfaces at Sacsayhuamán itself.
What happened to Sacsayhuamán after the conquest?
Sacsayhuamán from first walls to protection
1100s
Luis Lumbreras says carbon-14 dating places a Killke building phase here.
Mid-15th century
Work starts under Pachacuti or his son and continues under later rulers.
1533
Pizarro's forces take the city, then hold the fortress through an Inca siege.
1934
The ruins, buried by the Spanish, are excavated.
December 2025
The park marks 42 years as Cultural Heritage of the Nation and receives Mincetur's top tourism rank.
Garcilaso, writing within living memory, says the Spaniards pulled down the masonry inside the fortress to build their houses, so that "there is not a house in the city" without its stones; only the three great outer walls survived, because they could not be moved [3]. The encyclopedia adds that the Spanish covered the ruins in earth, and excavation came in 1934 [1].
Has it been reconstructed? What stands is a remnant, and no source here describes a rebuild. Garcilaso describes three towers inside the walls, the central one round [3]. The encyclopedia says their foundations can still be seen, along with the cisterns and aqueducts of the Suchuna area behind [1].
Today the site is the Sacsayhuamán Archaeological Park. Andina, Peru's state news agency, reports that on 22 December 2025 it marked 42 years as Cultural Heritage of the Nation under Law 23765, and that Mincetur gave it Jerarquía 4, its highest rank for a tourist resource [2]. More explainers are on the blog, and our about page sets out how we handle sources and corrections.
Frequently asked questions
Is Sacsayhuamán older than the Inca?
Parts of the site may be. Luis Lumbreras said in 2008 that carbon dating placed Killke construction in the 1100s, and a temple found that year showed pre-Inca and Inca phases [4]. Researchers following Alfredo Gamarra date the fitted walls much earlier still, to a lost age [6].
Were the stones melted or vitrified?
De Jong and Jordan argue that glassy patches are heat-made glaze, citing a lab test of one sample from a nearby cave [5]. Mainstream accounts describe pounding with harder stones and finishing with grinding stones and sand [1]. No published test of Sacsayhuamán's own joints settles it.
Did the Inca use mortar?
Not lime mortar. Garcilaso writes that they did not know how to make lime, and that on one wall they used a sticky red clay to fill small gaps [3].
Why is so little of the original complex left?
The Spanish took most of the stones for colonial Cusco and covered the ruins in earth [1].
Is Sacsayhuamán still used for ceremonies?
Yes. The ruins host the annual Inti Raymi reenactment festival at the winter solstice [1].
Sources
- Sacsayhuaman — World History Encyclopedia, Mark Cartwright (20 July 2016)
- Cusco: Sacsayhuamán es Jerarquía 4 y está al nivel de Machu Picchu como recurso turístico — Andina (24 December 2025)
- First Part of the Royal Commentaries of the Yncas, vol. 2 — Garcilaso de la Vega (1609), trans. Clements R. Markham, Hakluyt Society (1869), Internet Archive
- Ancient temple unearthed near Inca capital — The Associated Press via NBC News (14 March 2008)
- Evidence of Vitrified Stonework in the Inca Vestiges of Peru — Jan Peter de Jong and Christopher Jordan, grahamhancock.com (20 December 2011)
- The Cosmogony of the Three Worlds — Jan Peter de Jong, grahamhancock.com (18 February 2013)
- Could Ancient Peru And Egypt Have Been Connected? — Brien Foerster, Hidden Inca Tours (20 April 2014)