Comprehensive Study Notes on Machu Picchu

Geography and Architectural Foundation of Machu Picchu

• Geographic Location and Topography:

  • Machu Picchu is perched on a high ridge in the Peruvian Andes at an elevation of $8000\,\text{feet}$, situated $1600\,\text{feet}$ directly above the Urubamba River valley floor.
  • The settlement sits precariously on a narrow saddle between two towering peaks: Huayna Picchu and Machu Picchu mountain.
  • It lies within a cloud forest region—a wet, tropical mountain forest environment typically found at altitudes between $3000\,\text{feet}$ and $8000\,\text{feet}$.
  • The area receives approximately $79\,\text{inches}$ of rainfall annually.

• Core Structural Features:

  • Constructed without the use of the wheel, draft animals, or iron tools.
  • Contains over $600$ agricultural terraces designed to stabilize the hillside and prevent slope failure.
  • Includes more than $170$ central buildings, thousands of individual stone steps, several major temples, and $16$ interconnected gravity-fed fountains.
  • Built primarily from white granite quarried directly on site from a central, massive jumble of granite rocks.

• Engineering and Stonemasonry Techniques:

  • Ashlar Masonry: Important religious and administrative structures feature fine, mortarless stonework carved so precisely that after $500\,\text{years}$, a knife blade cannot be inserted between the courses.
  • Stone-Working Tools: Craftsmen used hammer stones composed of dense river rock—the hardest stone available—hauled up from the riverbed below. Some massive hammer stones weighed up to $30\,\text{pounds}$ and required two people to operate.
  • Mortar Utilization: While top-tier buildings relied purely on precise fitting and sheer weight, utilitarian or secondary buildings utilized a mortar mixture of clay, earth, and small stones.
  • Transportation of Monoliths: Blocks weighing up to $20\,\text{ton}$ were moved across steep terrain without ropes in tight quarters. Experimental reconstructions demonstrate that a $13\,\text{ton}$ stone can be maneuvered up a $25\%$ grade ramp and rotated $90^\circ$ using wooden sleds mounted on tracks, adjusted via log levers.

Rise and Fall of the Inca Empire

• Imperial Expansion Under Pachacuti:

  • The Incan Empire grew to become the most powerful society in the New World, spanning territory from modern-day Colombia to Chile—an area vastly larger than the Aztec Empire.
  • Rapid imperial expansion began in $1438$ under the rule of Pachacuti, a supreme warrior, political authority, and spiritual leader.
  • Pachacuti initiated major civil engineering and infrastructure projects, establishing cities, royal estates, temples, and an extensive transportation network.

• Infrastructure and Craftsmanship:

  • The Inca built and maintained approximately $14000\,\text{miles}$ of paved roads across South America to rapidly deploy military forces and regulate populations.
  • Incan artisans were master goldsmiths and silversmiths. Gold was revered as the symbol of Inti, the primary sun god.
  • Artisans crafted ceremonial knives, statues, gauntlets, masks, clothing, and gold sheets used to cover temple walls.

• Spanish Conquest and Destruction:

  • In $1532$, Spanish conquistador Francisco Pizarro landed in Peru with $180\,\text{men}$.
  • Learning that Emperor Atahuallpa was encamped at Cajamarca ($350\,\text{miles}$ away), Pizarro traveled to meet him.
  • On November $15$, $1532$, the Spaniards arrived at Cajamarca and invited Atahuallpa to a banquet. On November $16$, $1532$, Spanish forces ambushed the courtyard, slaughtering Atahuallpa's entourage and taking the emperor captive.
  • Atahuallpa offered a ransom: filling one room with gold and two rooms with silver up as high as his hand could reach. Gold was shipped directly from the capital city of Cuzco.
  • Despite receiving the full ransom, Pizarro executed Atahuallpa, sparking open warfare.
  • Superior Spanish armor and firearms overwhelmed Incan forces armed with wooden spears and clubs. The Incan population was already severely weakened by internal civil war and a smallpox epidemic introduced by Europeans.

• Retreat to Vilcabamba:

  • Following the collapse of the main armies, a member of the royal family named Manco led hundreds of Incas deep into the mountains to found a new capital city named Vilcabamba.
  • From Vilcabamba, the Inca waged guerrilla warfare against Spanish rule for several decades.
  • In $1572$, Spanish forces located Vilcabamba, executed the final royal Inca, and forced the abandonment of the city. More than $300000\,\text{Incas}$ died during the conquest period from war, famine, and smallpox.

Exploration and Rediscovery by Hiram Bingham

• The 1911 Expedition:

  • Hiram Bingham, a geographer and lecturer in history at Yale University (and descendant of famous missionaries), sought academic fame by locating the lost capital of Vilcabamba.
  • In July $1911$, Bingham set out from Cuzco into the Urubamba Cloud Forest along a newly cut trade path created by the Peruvian government.
  • Six days after departing Cuzco, Bingham reached Mandor Pampa at the base of Machu Picchu mountain, where he met an indigenous farmer named Arteaga.
  • On July $24$, $1911$, guided by Arteaga and a military escort, Bingham climbed the steep mountainside for $2.5\,\text{hours}$ through dense jungle growth. Near the summit, a young boy led Bingham directly to the overgrown stone ruins.
  • Bingham spent a few hours making a preliminary map and taking photographs before returning to camp at $5:00\,\text{p.m.}$ Initial impressions led him to believe it was not Vilcabamba due to its scale and layout.

• The 1912 Excavation Expedition:

  • Recognizing the potential significance of the site, Bingham secured funding for a full scientific expedition in $1912$, bringing archaeologists, a geologist, and bone specialist George Eaton.
  • Workers cleared the thick jungle vegetation to excavate the site. A total of $100\,\text{burial}$ caves were uncovered, yielding human skeletons, ceramic pottery, stone tools, and bronze knives.
  • George Eaton initially misidentified the vast majority of human skeletons as female.

• Early Theoretical Fallacies:

  • Virgins of the Sun Convent: Based on Eaton's initial skeletal assessment, Bingham hypothesized that Machu Picchu was a sanctuary for the Acllacuna ("Virgins of the Sun")—a cloistered group of chosen women living strict religious lives.
  • Cradle of the Empire: Observing the Temple of the Three Windows, Bingham theorized the site was the mythical origin place of the Inca, representing the three caves from which the founding Ayar Brothers emerged.
  • The Last Capital: Bingham maintained for much of his life that Machu Picchu was also the retreat city of Vilcabamba.
  • In $1913$, National Geographic published Bingham's photographic documentation (featuring over $100\,\text{images}$), catapulting the site to global fame. Bingham later became a U.S. Senator and passed away in $1956$ without knowing the true purpose of the site.

Terrace Systems and Environmental Engineering

• Subsurface Hydraulic Engineering of Terraces:

  • Terraces were designed to process heavy rain ($79\,\text{inches}$ annually) without destabilizing the mountain.
  • Each terrace wall averages $7\,\text{feet}$ in height and $10\,\text{feet}$ in width.
  • Stratified Construction Layers:
  1. Base Layer: Large, coarse rock backfill allowing rapid drainage and structural support.
  2. Intermediate Layer: Smaller stones covered by a layer of fine gravel.
  3. Filtration Layer: Sand layer placed above gravel.
  4. Surface Layer: Rich topsoil layer up to $3\,\text{feet}$ deep, manually carried up in baskets from the river floodplain $1600\,\text{feet}$ below.

• Agricultural Output and Capacity:

  • Machu Picchu contained approximately $12\,\text{acres}$ of terraced agricultural land within its urban perimeter.
  • Mid-1990s soil core analysis identified crop remains of maize (the primary crop), potatoes, and avocados.
  • Nutritional analysis indicates that the internal terraces could support a maximum of $55\,\text{people}$ with required calories, proving that the local population relied almost entirely on food imported from the lower Urubamba floodplains.

• Urban Hydraulic and Water Supply System:

  • Water was sourced from a natural spring located on the northern slope of Machu Picchu Mountain.
  • A stone-lined canal measuring $2450\,\text{feet}$ in length transported freshwater from the spring across the slope into the urban core.
  • Gravity powered a cascade of $16\,\text{sequential}$ stone fountains.
  • The channel gradient dictated the elevation of Fountain No. $1$, which directly governed the urban placement of the most critical structures (the Royal Residence and the Temple of the Sun).

Layout, Urban Sectors, and Sacred Features

• Sectorization of the City:

  • Divided into an Agricultural Sector and a $5\,\text{acre}$ Urban Sector, separated by a main central plaza.
  • Western Urban Sector: Contains high-status royal residences, major ceremonial temples, and the primary water access.
  • Eastern Urban Sector: Houses residential quarters for visiting priests, attendants, working families, and artisan workshops.
  • Main Entrance Gateway: Precise stone construction framing the distant peak of Huayna Picchu.

• Key Sacred Structures and Religious Ideology:

  • The Incas worshipped nature and natural formations known as huacas (sacred rocks, streams, and springs imbued with spiritual power).
  • Temple of the Sun: A semi-circular tower built directly over and around a massive natural granite rock (huaca). An eastern-facing window allows rays from the winter solstice sun to enter, splitting light across the carved stone interior to function as a precise solar observatory for agricultural scheduling.
  • Intiwatana Stone: A carved granite monolith sitting at the highest point of the sacred precinct. Translating to "the hitching post of the sun," it was used in winter solstice rituals symbolically binding the sun to the rock to prevent it from disappearing past the horizon. Similar structures at other sites were destroyed during the Spanish conquest.
  • Sacred Plaza: Features a large central rock carved in profile to precisely mirror the silhouette of the mountain peak directly behind it. Served as an assembly point for public rituals and addresses.
  • King's Group (Royal Palace):
  • Elite residential complex characterized by massive stone lintels weighing approximately $3\,\text{ton}$ each, placed over doorways without mechanical cranes.
  • Situated immediately adjacent to Fountain No. $1$, giving the resident primary access to the clean water canal.

Modern Scientific Consensus and True Purpose

• Debunking Early Theories:

  • Identification of Vilcabamba: In the early $1960\text{s}$, explorer Gene Savoy identified the actual site of Vilcabamba at Espiritu Pampa ("Plain of the Ghosts"), $50\,\text{miles}$ northwest of Machu Picchu. Bingham had briefly visited Espiritu Pampa in $1911$ but failed to see the full extent of the overgrown ruin.
  • Re-evaluation of Human Remains: Forensic anthropologist John Verano re-examined the skeletal collections at Yale's Peabody Museum. Using modern osteological criteria, he determined an equal balance of male and female skeletons, with clear evidence of females having borne children—completely disproving the "Virgins of the Sun" hypothesis.
  • Multi-Ethnic Workforce: Analysis of ceramic artifacts by Lucy Salazar and Richard Burger identified non-Inca pottery styles, including double-handled jars unique to the Colla ethnic group from the Lake Titicaca region (Peruvian/Bolivian border). The Colla were conquered builders brought in as specialized stone craftsmen.

• Identification as Pachacuti's Royal Estate:

  • In the late $1980\text{s}$, Berkeley anthropologist John Rowe discovered $16\,\text{th}$ century legal records in a Cuzco archive detailing a property lawsuit filed by descendants of Pachacuti.
  • The documents explicitly referred to a royal estate and sanctuary named "Picchu" belonging to the royal lineage (panaca) of Emperor Pachacuti.
  • Construction began around $1450$, roughly $80\,\text{years}$ prior to the Spanish invasion.
  • Climatic Motivation: Cuzco sits at an elevation of $11000\,\text{feet}$, subjecting residents to harsh winters. At $8000\,\text{feet}$, Machu Picchu is $3000\,\text{feet}$ lower, providing a significantly warmer climate for Pachacuti and his court.

• Demographics and Abandonment:

  • Permanent resident population was around $300\,\text{people}$, expanding to approximately $750\,\text{people}$ when the Emperor and his elite court were present.
  • The site was actively occupied from $1450$ until approximately $1540$.
  • Following the collapse of the central empire in Cuzco, Pachacuti's panaca (kinship group) lost the resources necessary to maintain the remote site and abandoned it. The imported artisans returned to their native provinces.
  • Cloud forest vegetation rapidly overgrew the structures, rendering the site invisible from the valley floor within a few years of abandonment and preserving it untouched until $1911$
  • Modern preservation efforts host over $300000\,\text{tourists}$ annually.