The Forgotten Tombs of Guirún and the search for the largest megalith in North America The valley of Tlacolula in Central Oaxaca, Mexico, is home to one of the largest concentrations of megalithic monuments in Mesoamerica. The origin of these structures is conventionally attributed to the Zapotec and Mixtec peoples, who occupied the area since at least 500 B.C. Their largest and most important sites were Monte Alban and Mitla, characterized by a sophisticated stone architecture, magnificent underground tombs and advanced metalworking techniques. The palaces and underground tombs of Mitla, with their intricate stone decoration, would cause the greatest impression in the early Spanish Conquistador and in later travelers during much of the 17th and 18th Century. Early chroniclers marveled at the extraordinary workmanship of these structures and the immense size of the stones – buildings which were “prouder and more magnificent than any that they had hitherto seen in New Spain. [1]” These early chroniclers described vast halls supported by round pillars consisting of one stone, and immense doorways built with huge monolithic lintels and jambs. An even greater marvel were the stone mosaics that ornated the walls, consisting of an infinite number of small rectangular stones “as smooth and regular as if they had all come from one mould”. And, more wonderful still, these stones were “adjusted without a single handful of mortar”, a feat “inexplicable even to the greatest architects”. All of this was accomplished, according to another source, wholly “without tools, with nothing but hard stones and sand. [2]” The palaces of Mitla and their impressive stone architecture have been covered at length in a previous article on this blog, which can be accessed here. A few years ago I came across a brief description and some black and white pictures of what appeared to be an enormous cruciform megalithic structure in the mountains near Mitla. The report in question had been published in 1909 by the American archaeologist Marshall H. Saville and only named the site as Guiaroo [3]. Initial enquiries into the location of the mysterious ruin in 2017 turned out to be largely unsuccessful. We were, however, able to locate another interesting megalithic tomb on the grounds of the abandoned Hacienda of Xaaga (See here for a description of our find). Finally, in March of 2020 our friend Ludovic Celle from Oaxaca City, who had himself visited the site a couple of years earlier and provided GPS coordinates, put us in touch with a local guide, Misael Martinez, who also knew the location of the ruins. His experience proved invaluable not only in locating the cruciform structure, but also a second tomb and various other ruined structures not mentioned by Saville in his initial report of the site. The "Palace" of Guirún, in the Upper Group. The Temple of the Two Rooms appears as a large stepped pyramid on the opposite side of the rectangular Plaza. The cruciform chamber is located on a ridge less than 200 meters from the Palace. [Photo by Author] The ruins of Guirún (or Guiaroo) are located on a hilltop some 5 kilometers to the NE of the little town of Xaagá, amidst spectacular cliffs and deep canyons. The site was studied by Gary M. Feinman and Linda M. Nicholas in 2004, which conducted a comprehensive survey of the remaining structures but did not conduct any excavations [4]. The largest building is called the “Palace of the Two Rooms”. It is in fact a group of four ceremonial structures facing a square plaza with a large terraced pyramid on the eastern side. The temple on the top of the pyramid is still in a reasonable state of preservation and consists of two large rooms approached by a stairway, from which the entire complex receives its name. The plan of the structure is similar to that of the largest palaces at Mitla, but lacks the same high-quality workmanship and stone decoration. It is quite possible that underground tombs may exist under each of the ceremonial platforms to the North and to the East. There are also traces of fortifications and of what could be a small Mesoamerican ball game to the South of the palace. The cruciform structure, often called a “tomb”, is found less than 200 meters from the main Palace, on another low ridge covered in bushes and shrubs, next to a ruined pyramidal mound some 10 meters high. A view of the Cruciform chamber looking North. [Photo by Author] Another view of the Cruciform chamber looking East. Note the immese size of the stone blocks forming the walls and the perfect jointing along the exposed face. [Photo by Author] There are few words to describe a structure so entirely unique in the panorama of Mesoamerican architecture. Its measurements are given by Saville as 32.8 ft. (10 meters) along the East-West axis and 28.6 ft. (8.7 meters) along the North-South axis. It is in the shape of a cross, precisely oriented to the cardinal directions, and has the entrance to the West. The walls, up to 2.5 meters (7.5 ft) high, consist of enormous megalithic stone blocks laid without mortar or cement. The largest stone block, located on the southern wall of the western arm, measures 12.5 by 3.3 by 3 ft, or approximately 3.8 by 1.0 by 0.9 meters, weighting an estimated 10 tons or more in its finished state. A total of 52 stone blocks were employed for the construction of the chamber, which remained unroofed. The interior walls, with the sole exception of the terminal wall of the southern arm, are entirely decorated with intricate geometric pattern resembling the mosaic stonework at Mitla – except that the carvings were applied here directly on the stone surface. The patterns run on three bands, the ones at the bottom and the top resembling waves or swastikas, with a labyrinthine design in the middle band. Traces of red and white paint still survive in places. The large stones were pinched into place by means of holes in the back of them, where levers were most certainly inserted. One huge stone block lying near the chamber also shows two enigmatic U-shaped bosses in relief that served possibly for transportation. The author posing next to the largest stone block on the souther wall of the western arm. [Photo by Author] A close-up view of the largest stone block on the southern wall of the western arm. Note the curious embossment in the middle, which probably served to ensure a tight fit the other stones. Similar features have been documented at other megalithic sites, such as at Ollantaytambo in Peru. [Photo by Author] Another view of the western and southern arm of the cruciform structure, each consisting of a single stone. Notice the holes in the back of the stones, possibly for the insertion of levers. [Photo by Author] It has been suggested that the “tomb” was left unfinished, due to the presence of several large construction blocks abandoned in the vicinity and the absence of a roof. This seems to contrast, however, with the evidence from the exquisitely carved decoration and traces of paint on the inside. Saville remarked that the debris filling the chamber at the time of discovery did not contain the slightest trace of human remains or other pottery fragments by which the structure could be dated. There is also no trace of a floor, so it is not clear whether the structure actually rests on bedrock or continues underground. Compass readings show that the longest arm is oriented about 17 degrees to the East of North. As such, Guirún would join a long list of Mesoamerican sites with anomalous orientations, including Teotihuacan, Chichen Itzá and Tula, which are all oriented between 15.5 and 17 degrees to the East of North. Our friend Ludovic Celle from Oaxaca also noticed a close similarity between the geometric patterns that ornate the walls of the cruciform structure of Guirún and those of the Palace of the Columns at Mitla. These differ significantly from the mostly plain decoration of other underground tombs, which only contain isolated mosaic panels. Ludovic also created a great 3D reconstruction of the tomb which may be accessed from the following link: https://www.artstation.com/artwork/kAG8y It is possible that the cruciform structure of Guirún was therefore never intended as a tomb, but as a ritual chamber or astronomical observatory. A view of the interior of the cruciform chamber, looking East, from which it is possible to appreciate the remarkable decoration on the inside. [Photo by Author] Another view from the interior of the cruciform chamber, looking North. It is possible to appreciate the three different patterns that form the lower, middle and upper band. [Photo by Author] At a distance of about one mile from the Upper Group and the cruciform structure, we found the remnants of another ruined palace supported by massive stone embankments. Inside the courtyard of this second palace we found the entrance to another tomb, which was also briefly described by Saville. This is a cruciform structure, measuring some 24 by 22 ft, or about 7.3 by 6.8 meters along its two horizontal arms, built entirely underground of loose cemented stones covered with a roof of large megalithic flagstones. The workmanship of this structure, which was most certainly a tomb, appears rather crude if compared to the other examples of cruciform tombs from Mitla and Xaaga, and does not share the least similarity with the exquisite finishing of the cruciform structure in the Upper Group, neither in the use of large megalithic stones nor in the quality of the decoration. The walls were covered in plaster and painted bright red and white. Only traces of the original plastering and paint remain. Of a third megalithic tomb described by Dupaix in 1805 as containing a monolithic stone pillar in the middle and carved mosaic panels, we could find no trace. The very narrow entrance to the other small cruciform chamber in the Lower Group of ruins at Guirún [Photo by Author] A view of the interior of the small cruciform chamber in the Lower Group. The roof is formed of enormous megalithic stone slabs, but the general construction appears quite crude. The walls still retain traces of red and white paint. [Photo by Author] Our attention was then drawn to some of the nearby quarries. A large prehispanic quarry was first reported by archaeologist Nelly Robles in 1994 at a site known as La Cuadrada, about one hour from Guirún, containing some 57 worked pieces. Unfortunately, the limited time available did not allow for a thorough examination of this site. Most of the stones seem to be of comparable size to some of the largest stone blocks at Guirún. We explored instead another stone quarry located near the village of Xaagá, near a rock face known simply as La Peña, where prehistoric rock art is also visible. We found there one very large stone, possibly a lintel, measuring approximately 4 by 1.5 by 1.25 meters. The approximate weight of the stone would be in the range of 15 to 20 tons. Our guide drew our attention to the fact that most quarries are located in close proximity to small streams, implying that water was perhaps employed to facilitate the cutting. A view of the megalithic stone quarry at the site of La Peña, near the village of Xaaga. [Photo by Author] The largest stone block still lying in the quarry at the site of La Peña, measuring some 4 meters long - most likely an unfinished lintel or pillar. [Photo by Author] We also learnt of one immense stone block lying on a mountain slope near the village of Unión Zapata, some 2 kilometers to the East of Mitla. The site is known as Guigosj, meaning “fallen stones”. Archaeologist Nelly Robles describes at least 6 huge stones “of uncommon size” lying horizontally in the quarry. In her 1994 report, Dr. Robles observed that “at first, the enormous size and monumentality of the stones made us doubt that these could have been quarried intentionally; yet the perfection of the cuts and their geometric shape indicated otherwise [5].” The largest stone would have had the enormous dimensions of 12 meters long by 4 meters wide and 2.5 meters high. Assuming a specific weight of the stone between 2.3-2.5 tons per cubic meter, its weight could be close to 300 tons. Also in this case, however, time limitations did not allow us to fully explore the site, which we will leave for a future expedition. Various large stones found abandoned in the vicinity of the cruciform structure in the Upper Group of ruins of Guirún. Note the holes in the back of the large lintel and the curious U-shaped bosses on the other stone block in the foreground - probably another transporation device. [Photo by Author] Judging from the enormous number of stones still abandoned in the quarries, and their immense size, it is clear that a colossal building program in the valley of Tlacolula and Mitla was suddenly interrupted and remained unfinished. In her 1994 study, Dr. Nelly Robles documented at least nine major quarries in the area of Mitla alone, containing an estimated 200 megalithic stone blocks in various stages of completion, the majority of which in the 5-10 tons range. This would be enough to build at least four cruciform structures like the one at Guirún. It is not clear what circumstances led to the abandonment of such a colossal building program. When the first Spanish Conquistadors visited Mitla in the 1520’s, they found the city already in ruins, after the Aztecs had conquered and sacked it in 1494. Perhaps it was the Aztec conquest that caused the abandonment of the quarries, or maybe this occurred much earlier. A recent 2019 study found evidence of a massive landslide to the north of Mitla that may have contributed to the abandonment of the site and the collapse of Zapotec civilization. The same study also found evidence of what could be buried pyramids or structures under the landslide, suggesting that the avalanche could have occurred within historical times [6]. Another mystery is the technique employed for cutting and transporting the enormous stone blocks. The stone itself is a type of andesitic toba, which would have required stone or metal tools for its extraction and polishing. A further question is posed by the intricate grecques and ornamentation found on some of the blocks – the finest being those that decorate the walls of the cruciform structure of Guirún. The perfect right angles and minute details suggest almost the use of molds, as the design is always repetitive and perfect, without the slightest error or deviation. One may also consider the possibility that the stone is in fact a type of geopolymer and that it was cast into place rather than quarried and transported. This possibility may only be confirmed by future studies and analyses. While this is only a suggestion for now, there is something in the obsessive repetition of geometric patterns and designs in the palaces of Mitla and the cruciform structure of Guirún that suggests almost a form of writing or a mathematical code, whose true meaning may however always escape us. A close-up view of some of the geometric patterns in the interior of the cruciform structure of Guirún. Were these intricate pattners carved or molded on the stone? [Photo by Author] The ruins of the valley of Tlacolula and Mitla represent a unique example of megalithic architecture displaying a workmanship and a tendency towards monumentality unknown in the rest of Mesoamerica. These magnificent structures appear as if out of nowhere, and are the expression of a tradition of working in stone that had already become extinct long before the time of the Spanish conquest. References [1] Toribio de Benavente Motolinia (1482-1568), Historia de los Indios de la Nueva España [2] Francisco de Burgoa, Geográfica Descripción, 1674 [3] Marshall H. Saville, The Cruciform Structures of Mitla and Vicinity, Putnam, 1909 [4] Gary M. Feinman and Lind M. Nicholas, Hilltop Terrace Sites of Oaxaca: Intensive Surface Survey at Guirún, El Palmillo and the Mitla Fortress, Field Museum of Natural History, Chicago, 2004 [5] Nelly M. Robles Garcia, Las Canteras de Mitla, Vanderbilt University, 1994, pp. 17-19 [6] V. H. Garduño-Monroy, et al., The Mitla Landslide: An event that changed the fate of a Mixteco/ Zapoteco Civilization in Mesoamerica, International Journal of Geophysics, vol. 2019, https://doi.org/10.1155/2019/5438381 Note: All the pictures on this page are intended for non-commercial use only and may be reproduced on other websites or publications so long as the source is cited. Exploration of the site was conducted with the help of certified guides to ensure the preservation of archaeological remains and the natural environment.