Stones Beneath the Altar: Why Spanish Cusco Sits on Inca Walls

There is a useful exercise on the Plaza de Armas in Cusco. Stand on the southeast corner, near the entrance to La Compañía de Jesús. Put one hand on the cathedral side of the wall and one hand on the Jesuit-church side. Look down. The lower courses of both buildings, sometimes the first six or eight feet of height, are not Spanish masonry. They are polygonal Inca stone, cut and fitted in the fifteenth century, supporting Spanish brick and adobe above. The seam is at about waist height. It runs around almost every block of the historic center.

Most Spanish colonial cities in the Americas do not have this seam. To understand why Cusco does, you have to follow the conquest in chronological order.

What Pizarro found

Francisco Pizarro's expedition of one hundred and sixty-eight men entered Cusco in November 1533. The Inca state had been in civil war since the death of the emperor Huayna Capac, probably of European-introduced smallpox, around 1527. His two sons, Atahualpa and Huascar, had spent five years fighting for the empire. Atahualpa had won the throne, then been captured by Pizarro at Cajamarca in 1532, ransomed for a room full of gold, then strangled. By the time the conquistadors reached the imperial capital, the Inca state was already politically broken. The military resistance came later, in 1536, and it nearly succeeded. But on the November day that Pizarro's men walked into the Plaza de Armas, the city was effectively undefended.

What they saw was a metropolis. The Temple of the Sun, Qorikancha, sat at the south end of town with its main chamber lined in over seven hundred sheets of solid gold, an estimated fourteen hundred kilograms. The walls of adjacent chambers were silver. The courtyard contained a life-sized golden garden: cornstalks with silver tassels, llamas with herders, butterflies, flowers. The plaza in front of them, Huacaypata, was paved with white sand carried by porters from the Pacific coast, three hundred kilometers and several five-thousand-meter passes away. The road system that converged here, the Qhapaq Ñan, ran for an estimated forty thousand kilometers across the Andes.

The Spanish stripped Qorikancha within weeks. The gold went into ingots and onto ships. The garden was melted down. By 1534 the imperial treasury of the largest empire in pre-Columbian America had been liquidated into bullion.

What remained were the walls.

What the walls were

Inca masonry of the imperial period, roughly 1438 to 1533, is not a building technique. It is a system. The blocks are cut from volcanic andesite, limestone, or, in the case of the most important structures, diorite from the quarries above Cusco. The stones are shaped by a long process of pecking with handheld stone hammers, fitting against an adjacent block, repecking the contact surface, refitting, until the joint is tight enough that a sheet of paper cannot slide into it. No mortar. Multiple planes of contact per block: six is the minimum, twelve is the maximum, and the famous Twelve-Angle Stone on Calle Hatun Rumiyoc is the documented limit case.

The technical achievement is the joint. The engineering achievement is the wall as a system. Inca walls survive earthquakes that flatten colonial buildings on the same parcel because the multiple-plane joints distribute lateral seismic force across many contact points. A masonry wall held together by mortar fails in a quake when the mortar cracks and the blocks slip. An Inca wall has no mortar to crack. The blocks shift slightly under load, then settle back into the same interlocking position because their faces will not let them rest anywhere else. The 1650 earthquake in Cusco destroyed much of the Dominican monastery built on top of Qorikancha. The Inca foundations did not crack. The 1950 earthquake destroyed much of the southern aisle of the cathedral. The Inca palace wall the cathedral was built on did not crack.

A wall that cannot be cracked is, by the standards of sixteenth-century European demolition technology, a wall that cannot be demolished. The Spanish in Mexico City had pulled down the Templo Mayor in 1521 by cracking it. They could not do the same in Cusco because the technique that worked on Aztec rubble masonry did not work on Inca interlocked polygons. They could remove the upper courses. They could repurpose the lower ones. They could not get rid of them.

So they built on them.

The cathedral on the palace

Construction on the Cathedral of Cusco began in 1559. The site was the palace of Inca Viracocha, the eighth Inca ruler. The choice of site was deliberate: our god stands on top of your emperor's house. The Spanish in the early colonial period made these substitution claims openly, both in chronicles and in built form. The colonial city was a theological argument made in stone.

The building material made the argument louder. The red granite blocks that face the cathedral were not quarried fresh. They were dragged from Sacsayhuaman, the great Inca fortress on the hill above the city, which had been partially decommissioned after the failed siege of 1536. The cathedral that occupies the most prominent site on the Plaza de Armas is, materially, an Inca fortress reassembled as a Catholic cathedral. The Inca palace foundation underneath is still there. The fortress stones above are repositioned Inca masonry. The Spanish contribution is mostly the upper courses, the bell towers, the wooden vault structure, and the interior fittings.

A few blocks away, the same logic plays out at La Compañía de Jesús. The Jesuit church, finished in its current form in 1668 after the 1650 earthquake destroyed the first version, sits on Amarucancha, the palace of Huayna Capac. The Bishop of Cusco complained to Pope Paul the Fifth that the Jesuit façade was so ornate it would outshine the cathedral on the same plaza. The Pope agreed and issued a decree ordering scale-back. The decree took years to cross the Atlantic, the isthmus of Panama, the Pacific, and the Andes. By the time it arrived, the façade was finished. The Jesuits kept their masterpiece. The Inca foundation underneath it kept the building standing through every subsequent quake.

What you can still touch

Calle Loreto, the narrow street that exits the Plaza de Armas beside La Compañía, is two original Inca walls facing each other. On the right is the wall of Amarucancha, the palace of Huayna Capac. On the left is the wall of the Acllahuasi, the institutional cloister of the Chosen Women, where selected young women from across the empire wove the textiles and brewed the chicha used in state ritual. After the conquest, the Spanish converted the Acllahuasi into the convent of Santa Catalina. They kept the walls. The Inca institution and the Catholic institution housed two different kinds of religious women, behind the same masonry.

A few blocks east, on Calle Hatun Rumiyoc, the Twelve-Angle Stone sits in the lower wall of the palace of Inca Roca, who reigned around 1321 to 1348. The stone is a block of green diorite, about a meter and a half across, with twelve cut and fitted angles, each in continuous joint with an adjacent stone. It has been in place for roughly seven hundred years. The palace above it is now the Archbishop's Residence. The wall has not shifted.

Qorikancha is the deepest reading. The Convent of Santo Domingo, built directly on top of the Inca temple in the 1530s and 1540s, occupies the upper half of the structure. The 1650 earthquake destroyed the colonial church above; the Inca walls beneath survived. Excavation has exposed four original chambers, dedicated to the Moon, the Stars, Thunder, and the Rainbow. The curved retaining wall of the Qorikancha enclosure, visible from Avenida El Sol, is one of the most precise pieces of stone-fitting in the Americas. It has not moved in five centuries.

What the stratification means

A walled city that cannot be demolished forces a particular kind of colonial settlement. The Spanish in Cusco could not erase the Inca capital because the Inca capital was structurally embedded in the new buildings they were trying to build. The conquest in Cusco produced overlay, not replacement. The result is not a syncretism in the romantic sense, where two cultures gently merge. It is a physical stratification, where one civilization's masonry sits on another's, in continuous direct contact, separated by a line of mortar.

The cultural and economic life of the city took the shape of the walls. The mestizo painting tradition of the Cusco School, exemplified by Marcos Zapata's Last Supper in the cathedral with its centerpiece of roasted cuy, runs on the same logic. European form, Andean substrate. The Inti Raymi festival, banned by the Catholic Church in 1572, returned in 1944 as a reenactment performed every June at Sacsayhuaman. The Quechua language, suppressed in colonial schooling, is still the first language of perhaps a quarter of the population in the wider region. The walls underneath have made room for the culture to do the same thing.

That is what the historic-center tour is walking. Eight stops, two and a half kilometers, two civilizations in continuous contact. The line is at about waist height on most blocks. Once you can see it, you cannot unsee it.