Scattered across the Peruvian Andes are architectural marvels that defy explanation. The Inca, masters of stone and landscape, engineered structures so advanced that they have survived for centuries.Their iconic masonrymassive, mortarless blocks shaped with stunning precisionis a testament to the power of the largest pre-Columbian empire in the Americas. From world-renowned citadels to remote jungle ruins, here are six must-see sites that reveal the incredible story of Inca architecture.Quick Guide to the Marvels of Inca ArchitectureSiteLocationBest for travelers whoKey featuresMachu PicchuAndes Mountains, Cusco RegionWant the iconic, all-encompassing Inca experience with breathtaking mountain viewsTemple of the CondorPrecision, mortar-free stoneworkSacsayhuamnOverlooking CuscoAre fascinated by massive-scale military architecture and unique natural rock formationsZig-zagging fortress wallsEnormous stone blocks (150+ tons)Natural rock slides (suchuna)QorikanchaCusco city centerWant to learn about the fascinating intersection of Inca and Spanish culturesOriginal Inca walls as the foundation of a conventTrapezoidal doorways and nichesOn-site museum with mummiesOllantaytamboSacred ValleyWant to explore a living Inca town and see a temple complex frozen in mid-constructionThe Wall of the Six MonolithsSteep agricultural terracesQullqas (storehouses) on the mountainsideRaqchiCanchis ProvinceAppreciate unique building techniques and want to see one of the tallest structures in the Inca Empire45-foot central temple wallMix of stone and adobe constructionCylindrical support columnsChoquequiraoVilcabamba mountain rangeEnjoy adventurous hikes and seek an off-the-beaten-path lost city with unique artistic detailsSunchu Pata ceremonial centerTerraces with camelid rock artRemote, uncrowded atmosphere1. Machu PicchuMachu Picchu, 2018. Source: Kristen JancukMachu Picchu tops every list of must-see sites in the former Inca Empire. Indeed, there is no better place to be completely enchanted by the Incas mastery of stone masonry, their coexistence with their natural environment, and their relationship with their gods and spirits.Most modern scholars believe Machu Picchu was built as an estate for Sapa Inca Pachucuti in the mid-15th century, and was actually called Huayna Picchu by the Inca themselves. Declared a UNESCO World Heritage site in 1983, many of its outbuildings, constructed of field stone, had crumbled and have since been reconstructed. Its larger buildings and temples, showcasing the Incas expert stone masonry, remained intact, as did many of the farming terraces.Machu Picchu is nestled in the valley between two enormous mountains, often shrouded by low clouds in the morning, adding to its air of mystery. Its buildings blend neatly into the surroundings, with features like the Temple of the Condor built directly into the rocky terrain.The Incas precision stone masonry, with large stone blocks fit together seamlessly using no mortar, as well as more subtle features of their architecture, like trapezoidal doors and windows, can be seen throughout the site. It also boasts an intihuatana stone, a rock sculpture that researchers believe the Inca used for astronomical purposes. It aligns perfectly with the sun at the solstices and likely had spiritual significance as well, connected to the worship of the sun god Inti.2. SacsayhuamnTrapezoidal doorway at Sacsayhuamn. Source: Peru TravelSacsayhuamn served as a fortress during the Spanish invasion. It overlooks the ancient Inca capital, Cusco, and is surrounded by a zigzagging wall of precision-cut stone.Much of the sites architecture was dismantled after the Spanish conquest, with colonizers repurposing the stone for their projects. What remains, however, is still impressive. It showcases the Incas renowned precision stone masonry, with some impressively large stone blocks thought to weigh over 150 tons.While the sites foundations were largely built into the existing rock, no one knows how the Inca managed to transport the enormous stone blocks there. According to Spanish chronicler Pedro Cieza de Leon, 20,000 men worked on the site, transporting the blocks with sturdy ropes.Sacsayhuamn was commissioned by Pachacuti, though it had been in use earlier by the Killke culture. Its distinctive zigzag shape is thought by some scholars to represent the head of a puma, a sacred animal in Inca mythology. Housing a temple to the sun, it was used for religious and ceremonial purposes in addition to offering protection for thousands should Cusco come under siege. After the Spanish took hold of Cusco, Sacsayhuamn served as a base for Sapa Inca Manco Capac as he fought to regain control.Natural rock slides at Sacsayhuamn. Source: Antipode PeruA particularlydistinctive feature of Sacsayhuamn is therodadero,in Spanish, or suchuna, in Quechua, bothmeaning slide. A natural rock formation incorporated into the site, these grooved and polished rock slides are zipped along by tourists todayand according to Garcilaso de la Vega, a 16th-century chronicler, they were used by the Inca Empires children for the same purpose 500 years ago. The site also hosts the annual Inti Raymi festival, a reenactment of the Incas winter solstice celebration.3. QorikanchaThe Convent of Santo Domingo was built over Qorikancha, with the original temple wall visible. Source: Peru HopWhen the gold-hungry Spanish invaders reached Cusco, they were no doubt delighted to lay eyes on Qorikancha. This complex included the empires most significant temple to the sun god Inti.Intis temple had gold-plated walls, golden ornamentation throughout, and an adjoining garden full of gold animal statues. The gold was ultimately stripped, possibly to ransom Atahualpa, whom the Spanish killed anyway. Most of the stone was dismantled and repurposed for new Spanish constructions, and the Convent of Santo Domingo was built atop what remained.What remains, however, showcases the Incas impeccable stonework and provides a unique example of an ancient temple. From the outside, the massive stone blocks that now serve as the foundation of the convent can be observedthey have remained standing for centuries, while the convent on top has had to be rebuilt multiple times after earthquakes.Inside, several original rooms remain and have been turned into a museum featuring many relics found during excavations at the site, including mummies. In addition to these artifacts, visitors can appreciate some of the unique elements of Inca architecture, including trapezoidal doorways and niches likely used to display the golden decorations the Spanish so coveted.4. OllantaytamboA birds eye view of the Ollantaytambo complex. Source: Peru TravelIn what is today referred to as the Sacred Valley, the Inca conquered a number of smaller cultures and established thriving estates at key sites to control the valley.Ollantaytambo is believed to have been occupied by the Huari for several hundred years before the dramatic expansion of the Inca Empire began. Here, the Sapa Inca built a personal estate and began constructing a temple complex. During the conquest, Ollantaytambo acted as an important stronghold for Manco Capac, who, according to Spanish sources, amassed a large army and fought back against the Spanish advance, employing a clever tactic to flood the plain below and mire the Spanish horses in mud.Nestled between towering mountain peaks, the Ollantaytambo complex features the Incas reinforced terraces and a mix of finished and unfinished structures. Carved stone blocks are scattered around the base. Some are mostly untouched, while others are intricately carved into precise shapes with double jambs, suggesting further construction was underway when the site was abandoned.Qullqu or storehouse built into the mountainside at Ollantaytambo. Source: Photo by author Kristen JancukA climb to the top of the steep terraces reveals the incomplete Temple of the Sun and the Wall of the Six Monoliths. Enormous stone blocks standing over twelve feet tall are fitted precisely together, with no indication of how the Inca managed to get them up there. The view from the top gives visitors a peek at the famous qullqas, storehouses built into the sides of the mountains. These once appeared all over the empire along the Qhapaq Nan.5. RaqchiThe remains of the Temple of Viracocha at Raqchi. Source: Peru TravelRaqchi is located about 70 miles south of Cusco. It was occupied by pre-Inca cultures, including the Wari, before being taken over by the Inca. The god Viracocha, a creator god worshiped by a number of pre-Inca cultures, was said to have performed a miracle here. He led his people, the Canas, to create a shrine, or huaca, to him.When Sapa Inca Huayna Capac, the last true Sapa Inca who ruled just prior to the Spanish conquest, saw the shrine and heard the story of the gods miracle, he decided a more impressive dedication was needed. He began construction of a temple and housing for religious figures, such as priests and nuns (called mamacona and yanacona).What remains of this temple is a 45-foot-high central wall. It stands in sharp contrast to other important Inca sites in its use of both stone blocks and adobe. Precision-shaped stones form a sturdy base for the adobe bricks, with both sections of the wall featuring the Incas distinct trapezoidal doors and windows.The remains of cylindrical columns that once supported the temple, their sturdy stone bases, can also be seen. The height of the wall is particularly noteworthy because most Inca constructions were only one story. This height may have made it one of the tallest buildings in the empire.Other structural remains in the area include round qullqas. These are noteworthy because they are not made in the traditional Inca shape or style. Researchers suggest they may have remained from an earlier culture and were perhaps repurposed when the temple project began.6. ChoquequiraoRock art at Choquequirao. Source: National GeographicChoquequirao, meaning cradle of gold in Quechua, was integral to coca cultivation, a much-maligned plant sacred to the Inca. It may have also provided refuge to the Inca resistance during the conquest. Because of its remote location, it remained lost for centuries, and excavations have barely scratched the surface of what archeologists believe lies beneath the dense vegetationexcavations began in the 1970s, and an estimated 30% has been uncovered.What can be seen so farby those willing to make the multi-day trek, as there is no road or rail accessincludes temples, residences, extensive terraces, and Sunchu Pata, a flattened hilltop ringed with stones that likely served as a ceremonial center. The materials used differ from those at Machu Picchu, ultimately impacting the architecture. In the area, a more fragile rock could not be shaped into the large stone blocks seen elsewhere in the empire.One of the truly unique features of Choquequirao is its rock arta whimsical contrast to the Incas typical staid stone structures. The sites terraces have a series of parading camelids (llamas, alpacas, or vicuas, all native to the region and very similar looking) built into them. Some scholars suggestthat this indicatesworkers from the Chachapoya culture were involved in the sites construction, as this style of rock art was unique to them during thatperiod. A white quartzite stone was used for this rock art, making it not only stand out but also reflect the morning sun, shining back at the Incas most important god.