Machu Picchu - The secrets of the Inca builders | DW Documentary

Key Concepts

Machu Picchu: A 15th-century Inca citadel located in the Andes Mountains of Peru, renowned for its architectural marvels and intact preservation.
Inca Empire: The largest empire in pre-Columbian America, flourishing in the 15th century and ruling approximately 10 million people.
Quechua: The main language of the Incas.
Pachacuti: The first Inca Emperor, believed to have commissioned the construction of Machu Picchu.
Hanan and Hurin: The upper and lower districts of Inca cities, respectively, reflecting the Andean concept of duality.
Kapak Nan: The main Andean road system, a vast network connecting the Inca Empire.
Terraces: Sculpted agricultural platforms on mountainsides used for farming and construction.
Drainage System: An intricate underground network designed to manage rainwater and prevent landslides.
Ashlar Walls: Walls constructed from perfectly aligned, regular-shaped blocks.
Cyclopean Walls: Walls made of huge, irregularly shaped blocks that fit together perfectly.
Intihuatana: A ceremonial altar believed to be an astronomical observation point, meaning "hitching post of the sun" in Quechua.
Mita System: A labor tax system where subjects provided a period of service to the state.
Carbon-14 Dating: A scientific method used to determine the age of organic materials.
Khipus: Knotted cords used by the Incas for recording information.

Machu Picchu: An Inca Architectural Marvel

Discovery and Historical Context

Machu Picchu, situated in southern Peru at an altitude of 2,430 meters, is a testament to the architectural prowess of the Inca civilization. Discovered by American explorer Hyram Bingham in 1911, the vast ruins were largely unknown to the Western world. The city, known as "Yuca in Quechua," is believed to have been built during the reign of Pachacuti, the first Inca Emperor, in the 15th century. The Inca Empire at its peak encompassed nearly 10 million people. Unlike most other Inca ruins, Machu Picchu remains remarkably intact because the Spanish conquistadors never reached the site, thus preventing its plunder for treasure and gold. The city is thought to have been abandoned during the Spanish conquest, with only a few farmers residing there by the time of Bingham's arrival.

Architectural Design and Layout

Machu Picchu is built on a steep ridge between the peaks of Machu Picchu and Huayna Picchu, covering over 32,500 hectares. Archaeologists have divided the site into two main sectors: urban and agricultural.

Agricultural Sector: This sector features a network of terraces that sculpt the mountainside, creating over 10 hectares of flat land for farming and construction. Buildings like the Guardian's House overlook the valley.
Urban Sector: This sector is characterized by the typical Inca architectural style, divided into an upper district (Hanan) and a lower district (Hurin). The Hanan district typically houses the most spectacular monuments, while the Hurin district served more utilitarian purposes. This division reflects the Andean concept of duality, aiming for harmony through the marriage of opposites. The Hanan and Hurin districts are separated by a main square, measuring 90 meters by 25 meters, which served as a gathering place for ceremonies.

Engineering Challenges and Solutions

The construction of Machu Picchu presented immense engineering challenges due to the jagged mountain terrain, steep precipices, and a challenging climate with up to 2,000 mm of rain annually.

Terracing and Land Sculpting: The Incas meticulously sculpted the mountainside, creating terraces to stabilize the slopes for construction and cultivation. This process transformed rugged landscapes into habitable and fertile ground.
Drainage System: Recognizing the danger of landslides caused by heavy rainfall, the Incas developed an ingenious underground drainage system. This system, integrated within the terraces, evacuates rainwater, preventing soil erosion and structural collapse. Studies reveal the terraces are composed of layers of stones, gravel, sand, and fertilized soil, allowing water to percolate through and drain to the valley below. This system is crucial for the city's stability, preventing it from being washed away.
Foundations and Underground Work: It is estimated that over half of the human effort invested in building Machu Picchu was dedicated to constructing these foundations and the underground drainage system.

Construction Techniques and Materials

The Incas demonstrated exceptional skill in quarrying, cutting, and transporting granite blocks, some of them enormous, without the use of wheels, iron, or steel.

Quarrying and Stone Transport: The primary raw material was granite, extracted from local quarries. Techniques for transporting blocks included pulling them with ropes and human strength along beds of sand or clay, using systems resembling wooden ladders with levers, or rolling them on stone cylinders.
Stone Assembly and Finishing: The true genius of Inca stonemasonry lies in the assembly and finishing of the walls. Blocks were meticulously honed to fit perfectly, often with a thin layer of sand between them, making the joints almost invisible. The trial-and-error technique was employed, with sand spread on the surface of a block to rework parts of the stone until a perfect fit was achieved.
Wall Types: Different wall constructions were used depending on the structure's purpose. Basic walls were built with mortar, while more precise structures featured Ashlar walls (regularly shaped blocks) or Cyclopean walls (huge, interlocking blocks). The walls are fused with the rock, providing exceptional resistance to earthquakes.
Building Longevity: The construction methods employed ensured the longevity of the structures, with some walls estimated to have taken around 8 years to build in the initial phase. Machu Picchu houses 172 buildings, serving administrative and religious functions.

Strategic Location and Resources

The choice of location for Machu Picchu was strategic, offering access to vital resources and a defensible position.

Ecological Advantages: Situated in the Vilcabamba region, on the edge of the Amazonian rainforest and the Andes, Machu Picchu had access to diverse resources. The upper jungle provided cocoa, medicinal plants, and exotic bird feathers, while lower regions offered gold and silver. The Andes provided essential produce like corn, quinoa, llama meat, and over 3,000 varieties of potatoes.
Connectivity via Kapak Nan: Several roads led from Machu Picchu, connecting it to approximately 60 nearby settlements. These routes were part of the Kapak Nan, a vast pre-Columbian road network spanning nearly 30,000 km, which facilitated the transport of goods and manpower, maintaining Inca order and power.
Sacred Landscape: The dramatic natural surroundings, including towering granite mountains, the Urubamba canyon, and the Amazon on the horizon, contributed to the site's sacredness. The Incas revered the landscape, viewing mountains as ancestral protectors. The location also served to impress subjects with the Incas' capabilities.

Astronomical and Religious Significance

Machu Picchu's architecture is deeply intertwined with astronomical observations and religious practices.

Astronomical Alignment: Many buildings exhibit specific orientations aligned with celestial events. Astronomy played a crucial role in the Inca calendar, determining agricultural cycles and rituals.
Intihuatana: This ceremonial altar, meaning "hitching post of the sun," is positioned to align with the sun's movement during solstices and equinoxes, casting shadows that indicate specific times of the year.
Temple of the Sun: This temple features a semi-circular wall and is believed to have been used for astronomical observations. While the sun illuminates an altar within, research suggests the precision for exact solstice calculations might not have been achievable, indicating its use for rituals rather than precise astronomical astronomy.
Sacred Monuments: Other monuments were built in relation to the sun's position, likely for rituals marking important moments in the Inca calendar.

Labor and Workforce

The construction of Machu Picchu was made possible by the vast workforce controlled by the Incas, primarily through the Mita system.

Mita System: This labor tax required subjects to provide one to two months of service annually to the state, contributing to large-scale architectural projects. This system provided both skilled labor and brute force for construction.

Preservation and Durability

Despite centuries of weathering, Machu Picchu's structures have endured due to their robust construction and the Incas' foresight.

Colored Renders: Some walls in the lower city retain traces of colored clay renders, applied to insulate buildings from the cold and conceal stone joints.
Water Management for Longevity: The comprehensive drainage system, diverting rainfall and managing water flow, was crucial for the city's durability. Researchers estimate the urban sector could drain 13,000 liters of water per hectare annually.
Water Supply System: The Incas also engineered a sophisticated system to transport water from natural sources to the city for daily and ceremonial use. A 749-meter canal, with a gradient of 2-5%, supplied water to various fountains, including those near the Temple of the Sun for ceremonial purposes and others for domestic use. These fountains could deliver between 25 and 125 liters of water per minute, even during the dry season.
Unfinished Projects: Evidence of unfinished canal sections suggests the Incas were continuously improving and adapting their infrastructure.

Dating and Timeline

The precise dating of Machu Picchu's construction has been a subject of ongoing research.

Traditional Dating: Historically, Machu Picchu was believed to have been built after 1450. This timeline was based on interpretations of historical texts and administrative documents, such as those compiled by John Howland Rowe, which suggested Pachacuti began his conquests in 1438.
Carbon-14 Dating: In 2020, Polish researchers, in collaboration with teams from Peru and New Zealand, re-examined these dates using carbon-14 dating on samples from Machu Picchu, including ropes, textiles, and corn. These samples, related to the initial occupation and construction phases, indicated that the Incas may have started building around 1420, several decades earlier than previously estimated. This finding challenges the established Inca timeline and suggests the Inca Empire may have lasted longer than a century.

Conclusion

Machu Picchu stands as an unparalleled testament to the ingenuity, engineering prowess, and deep understanding of their environment by the Inca civilization. The site's remarkable preservation, strategic location, sophisticated infrastructure, and astronomical alignments highlight the Incas' ability to harness natural resources and celestial phenomena to create a city that was both functional and sacred. The ongoing research, particularly through scientific dating methods, continues to refine our understanding of this extraordinary achievement, solidifying Machu Picchu's status as one of the world's most impressive archaeological feats.