Machu Picchu is one of the most studied archaeological sites in the world and at the same time one of the least understood in terms of its specific function. The Incas did not leave behind alphabetic writing, and most of the colonial documents describing the Empire were produced by Spaniards who never reached the site. That means archaeology, architecture, astronomy, and the analysis of skeletal remains are the only sources available to reconstruct what the people who lived and worked at Machu Picchu actually did. The conclusions drawn from those sources are fascinating, but none of them is definitively settled.
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The most accepted theory: Pachacutec’s royal estate
The interpretation with the strongest support among archaeologists today is that Machu Picchu functioned as a llaqta, which in Quechua means settlement or place of residence, directly linked to the Inca ruler Pachacutec. It was not a political capital or a city in the modern sense, but a royal estate where the Inca and his court traveled at certain times of the year for rest, ceremonies, and the administration of the surrounding territories.
That interpretation is supported by several elements in the archaeological record. The exceptional quality of the stonework in the main structures, especially the Temple of the Sun and the Sacred Plaza, indicates that it was built to host people of the highest rank. The water system with 16 ceremonial fountains with continuous flow was a luxury that only made sense in spaces used by royalty. And the size of the complex, capable of housing between 300 and 1,000 people according to estimates, is consistent with the retinue that accompanied an Inca ruler on his journeys.
American archaeologist Lucy Salazar and Peruvian archaeologist Richard Burger published a study in 2004 that reinforced this interpretation and remains one of the main reference works on the function of the site. Their analysis of the spatial distribution of the structures and the objects found in Bingham’s excavations consistently points to a use connected to the political and religious elite of the Empire.
Ceremonial and religious center
The religious dimension of Machu Picchu is inseparable from any theory about its function. The Incas did not distinguish between politics, religion, and administration in the way modern societies do. The Inca ruler was considered the son of the sun, Inti, and his residences were also sacred spaces where ceremonies of the Inca ritual calendar were performed.
The Temple of the Sun is the most elaborate structure at the site and the only one built on top of a natural curved rock that the Incas incorporated into the design of the building. Its serpentine window is oriented to receive sunlight exactly during the winter solstice on June 21, when the rays of dawn enter through the opening and fall on the stone at a precise angle that occurs only on that day of the year. That deliberate astronomical alignment indicates that the building had a ceremonial function linked to the Inca solar calendar.
The Sacred Plaza, together with the Temple of the Three Windows and the Main Temple, forms another top level ceremonial complex. The Intihuatana at the top of the urban sector functioned as a point of astronomical observation and as a central element in rituals tied to the agricultural and solar calendar. The presence of these highly symbolic spaces, strategically distributed throughout the complex, indicates that the religious dimension was one of the site’s central purposes, not an accessory to its other functions.
Astronomical observatory
The architecture of Machu Picchu has astronomy built into it in a way that modern astronomers and engineers are still studying. In addition to the solstice alignment of the Temple of the Sun, there are other elements at the site that seem to have been designed for the observation and recording of celestial phenomena.
The Sacred Rock at the northern end of the citadel has a silhouette that, when viewed from certain angles, mirrors the profile of Yanantin Mountain rising behind it on the horizon. That correspondence between earthly and celestial forms is consistent with the Andean worldview in which mountains, rivers, and heavenly bodies form an interconnected system.
The Intihuatana has been interpreted as a solar gnomon that made it possible to calculate solstices, equinoxes, and other moments in the agricultural and ritual calendar. The Quechua word used to name it refers to the act of tying the sun, a metaphor describing the function of that point as an anchor of cosmic time within the Inca belief system.
The astronomical function of the site does not rule out the other interpretations. It is likely that astronomical knowledge served both the religious dimension of the site and the agricultural planning of the terraces surrounding it.
Agricultural production center
The terraces surrounding Machu Picchu are not just a scenic feature. They are a sophisticated work of agricultural engineering that required generations of accumulated labor and produced crops under conditions that would have been impossible on that mountain terrain without those terraces.
The terraces regulate soil temperature, control erosion, allow excess water to drain during periods of heavy rain, and create differentiated microclimates that the Empire used to experiment with different plant varieties at different elevations. Some researchers propose that Machu Picchu was partly an agricultural experimentation center where crop varieties were tested under controlled conditions before being extended to other parts of the Empire.
The Moray complex, located a few miles away in the Sacred Valley, is the clearest example of that Inca agricultural laboratory function. Machu Picchu may have had a similar complementary role through its network of terraces and water system.
Sanctuary of the acllas
One of the lesser known theories, but one supported by the skeletal record, is the one linking Machu Picchu to the acllas, women chosen by the Inca state to perform ceremonial functions, produce elite textiles, and prepare ritual chicha.
Analysis of the skeletal remains found in the site’s cemeteries revealed an unusually high proportion of women compared to men. Bingham initially interpreted that evidence as proof that Machu Picchu was a sanctuary of virgins of the sun, an interpretation later archaeologists moderated but did not completely dismiss.
The significant presence of women in the skeletal record is indeed consistent with the existence of acllas at the site, although the most recent analysis of the same material suggests that these women came from different parts of the Empire and were of different ages, which is not entirely consistent with the profile of acllas as described in colonial sources.
Strategic control point
The location of Machu Picchu is not accidental. It stands at the edge between the Andean highlands and the Amazon rainforest, at a point from which the routes connecting both regions can be visually controlled. Access to the site from the Sacred Valley passes through natural control points that the Incas took advantage of with their roads and stone gate systems.
That strategic position has led some researchers to propose that Machu Picchu also had a territorial control function over exchange routes between the highlands and the rainforest. Products from the Amazon that the Inca Empire used in its rituals and economy, such as tropical bird feathers, medicinal plants, wood, and animals, entered through those routes, and Machu Picchu may have served as a point of redistribution and control for that flow.
Why it was abandoned
The abandonment of Machu Picchu is as mysterious as its function. There is no evidence of violent destruction or natural catastrophe to explain why the site was left to the vegetation. The most accepted explanation is that the collapse of the Inca Empire after the arrival of the Spanish, together with the death of Pachacutec as head of the royal panaca that sustained the site, left its maintenance and occupation without purpose.
In the Inca system, royal estates and their resources were administered by the panaca, the ruler’s family lineage, even after his death. The worship of the deceased ruler and the maintenance of his properties were collective obligations of the panaca. When the Empire collapsed and the panacas lost their economic and political power, the sites linked to specific rulers were gradually abandoned.
Machu Picchu was probably vacated progressively between 1530 and 1550, without violence and without any single person deciding it, simply as a consequence of the dismantling of the system that sustained it. The cloud forest vegetation did the rest within a few decades.
What we still do not know
The archaeology of Machu Picchu is not settled. There are sectors of the site that have not been systematically excavated, and there are questions that the available evidence does not answer clearly. We do not know with certainty how many people lived at the site during its peak period of activity. We do not know whether the 16 ceremonial fountains had a specific ritual order of use or whether they were for general access. We do not know exactly what kinds of ceremonies took place in the Sacred Plaza or what ritual objects were used there because most of them were taken to Yale during Bingham’s expeditions.
What we do know is enough to understand that Machu Picchu did not serve a single function, but several that coexisted in one space: the ruler’s residence, a ceremonial center, an astronomical observatory, an agricultural complex, and a territorial control point. That multiplicity of functions is characteristic of major Inca settlements and is what makes the site feel inexhaustible for the visitor who arrives wanting to understand, not just to take pictures.
Peru Sites explains Machu Picchu with guides who know the theories
At Peru Sites, we coordinate official guides with training in Andean archaeology who explain the different interpretations of the site during the tour, point out the architectural elements that support each theory, and answer the questions the site raises. For a first visit, that context is what transforms the experience.
