Part I - The Valley of Mexico
“A great, scientific instrument lies sprawled over the entire surface of the globe. At some period, thousands of years ago, almost every corner of the world was visited by people with a particular task to accomplish. With the help of some remarkable power, by which they could cut and raise enormous blocks of stone, these men created vast astronomical instruments, circles of erect pillars, pyramids, underground tunnels, cyclopean stone platforms, all linked together by a network of tracks and alignments, whose course from horizon to horizon was marked by stones, mounds and earthworks”
[John Michell, The New View over Atlantis, Thames & Hudson, Reprinted 2001]
This is the first part of a series of articles on what will be considered by many as a very controversial subject. The topic is that of the alignment and placement of ancient sites. There are many theories and speculations on why a particular location was chosen for the placement of ancient pyramids, ancient temples and sanctuaries, ranging from Giza’s Orion correlation theory to New Age beliefs in the existence of such things as ley lines and Earth energies.
A number of studies and the advances in the still relatively new discipline of archaeoastronomy have revealed important elements of the connection between the ancients and the Sky. Nevertheless, when this approach is applied outside of a single site or landscape feature to encompass multiple ancient sites (as in the case of the Egyptian pyramids or the ancient city of Angkor, in Cambodia), the results are, at best, controversial.
Even more controversial is the idea that the placement of ancient sites, even over very long distances, would be ruled by geodetic or mathematical proportions having little or no connection at all with the local geography or other strategic reasons usually advocated for explaining the location chosen for the founding of a city or a temple.
Geodesy, that is the science of measuring of the Earth, is not something commonly ascribed to ancient civilizations. The accurate determination of latitude and longitude has only been possible in relatively modern times, with the invention of precision chronographs. While latitude can be calculated with sufficient accuracy with the help of a quadrant or astrolabe, by observing the altitude of the sun or of certain “fixed” stars above the horizon, the problem of longitude remained without a solution until the invention of the marine chronometer in 1773. 
Without such knowledge, establishing a “grid” or network of ancient sites over a large enough area would have been highly unpractical, if not impossible. This is why such a theory of long-distance alignments of ancient sites – which would moreover need to take into account the curvature of the Earth or some advanced surveying and projection techniques believed to be the exclusive domain of modern science - is nowadays utterly dismissed as a wishful fantasy.
This often turns into a circular argument. Because no ancient civilization clearly possessed the scientific or technological instruments required to achieve such precision alignments, then any alignment must be the product of chance or coincidence. This is, not to speak of the reason why ancient civilizations should have deliberately placed their sacred sites along a grid or system of geodetic and landscape alignments of some sort. More on this later.
Three Pyramids and a “Star” Mountain
Ancient Mexico is an excellent ground for the study of ancient alignments. Not only do we find a continuity of civilization and beliefs going back thousands of years, from the Aztecs, Toltecs, Maya and Teotihuacan, down to the mysterious Olmecs; but we also find more pyramids than in any other Country in the world to verify such a theory (there are no accurate estimates, but the number might easily be in the thousands).
The Valley of Mexico, with its vast flat plain once occupied by the ancient lake of Texcoco and surrounded by high mountains, will be the perfect setting to verify our theory of alignments.
When drawing on a map the major ancient sites around the Valley of Mexico, almost immediately an interesting pattern starts to emerge.
There are three major Aztec pyramids within the boundaries of present day Mexico City: these are the Templo Mayor of México-Tenochtitlán, the Templo Mayor of Tlatelolco and that of Tenayuca.
All these constructions share very similar characteristics: they were built around the same time period, between the XIV and the early XVI Century AD, and were all subject at some point to Aztec rule, erected by people sharing a similar system of myths and beliefs. They all consist of a large pyramid platform, surmounted by a double sanctuary and enclosed within a sacred precinct. Let me state this again: These are the three largest pyramids within present day Mexico City, and are virtually identical in construction and design ; yet, no one has apparently noticed (up to this day), that they are also very precisely aligned among each other.
Let’s take a closer look:
The great Aztec capital of Tenochtitlán was built on an island in the center of the lake of Texcoco, subsequently enlarged with the construction of artificial dykes and canals. At the very center of the City, within the sacred precinct, was the great Teocalli, the Templo Mayor, with its twin sanctuaries dedicated to the gods Tlaloc and Huitzilopochtli. Built as a massive pyramid, the temple had at least seven stages of construction, dating from 1337 to 1521 AD. At its peak, the temple measured 100 by 80 meters at its base, and reached between 45 and 60 meters in height. Its impressive ruins, discovered in 1978 after centuries of abandonment and deliberate destruction, are still one of the major tourist attractions in downtown Mexico City.
Tlatelolco was a sort of sister city to México-Tenochtitlán, also built on an island in the lake of Texcoco. The city itself was founded by a dissident Aztec faction only 13 years after the founding of México-Tenochtitlán, in 1338 AD. Like the Templo Mayor of its sister city, also the great pyramid of Tlatelolco underwent several construction stages – at least seven, whose imposing ruins still survive in what is today Plaza de las Tres Culturas. The last construction stage had similar dimensions to the Templo Mayor of México-Tenochtitlán, measuring some 80 by 70 meters at the base, and also included a double sanctuary at the top dedicated to the gods Tlaloc and Huitzilopochtli.
Tenayuca was an old settlement of the Chichimecas, whose foundation might be traced back to as early as 1064 AD. The last stage of construction of this pyramid, which was likely the prototype of all later Aztec pyramids, measured 68 by 76 meters at its base, and also underwent several stages of construction and reconstruction (at least eight). Also at Tenayuca, a twin stairway led to the double sanctuary on top of the massive pyramid. Interestingly, the pyramid of Tenayuca does not share the same equinoctial orientation as the Templo Mayor of México-Tenochtitlán and Tlatelolco, but is rather oriented towards the setting of the star Aldebaran, in the constellation of Taurus, 17 degrees north of the ideal East-West orientation on the day of the passing of the Sun at its zenith. 
The Alignment Tenayuca – Tlatelolco – Tenochtitlán – Cerro de la Estrella
|The main system of ancient alignments around the Templo Mayor of México-Tenochtitlan. [Reconstruction by Author, courtesy Google Maps]|
It is easy to realize that a line drawn through the summit of the Templo Mayor of México-Tenochtitlán and the Templo Mayor of Tlatelolco would terminate exactly on the main sanctuary of the pyramid of Tenayuca.
To further confirm and reinforce the existence of this alignment, it should be noted that one of the major road arteries in present day Mexico City, the Calzada Vallejo, follows exactly this same alignment between Tlatelolco and Tenayuca. This is not surprising, given that the modern road follows the track of one of the ancient causeways that crossed the – now dry - lake of Texcoco in Aztec times.
A prolongation of this alignment towards the South-East also leads to another very important landmark in Mexico City. This time, it is not a pyramid, but rather a steep, forested hill called Cerro de la Estrella. Again, this can be no chance: The Cerro de la Estrella played a very important role in the sacred geography of the Valley of Mexico, as it is the spot where the Aztecs celebrated the New Fire ceremony every 52 years, at the end of each calendar cycle and the beginning of a new one.
The etymology of the name is unclear; Cerro de la Estrella meaning “Mountain of the Star”, supposedly after a colonial hacienda by the same name built on its slopes soon after the Spanish conquest of Mexico. The ancient name of the hill, which rises 224 meters above the surrounding plain, was Huizachtecatl, meaning a forested hill in ancient Nahuatl. Yet the highly evocative name of “Mountain of the Star” could have a much more profound astronomical significance that we do not yet fully understand.
A pyramid was built by the Aztecs on top of the Cerro de la Estrella, but the occupation of the site dates back at least 3,000 years. A large settlement occupied the slopes of the hill between 100 and 650 AD, contemporary with the rise of the power of Teotihuacan in the valley of Mexico, on the North-Western shore of the lake of Texcoco.
Interestingly, the alignment would not appear to point towards the summit of the hill, but rather deviates a couple of degrees to the West towards a little eminence on its Western slope.
In 2006, a massive pyramid was discovered on the Northern slopes of Cerro de la Estrella, measuring as much as 150 meters at its base, one wonders what might still lie buried at this fascinating site. 
The picture expands
For how interesting the alignments we have discovered so far, these would have been certainly within the technical capabilities of the Aztecs: The longest distance in the alignment, that is the one between Tenayuca and Cerro de la Estrella, is only 22.5 Km, meaning that the hill would have been within a clear line of sight connecting Tenayuca to the great temples of Tlatelolco and Tenochtitlán. This was even truer in ancient times, without the pollution and haze of modern day Mexico City.
Interestingly, the Templo Mayor of Tenochtitlan is located exactly at the same distance of 11.3 Km from Tenayuca and Cerro de la Estrella, being at the exact center of the imaginary line connecting these two points (1:1).
And what about the position of Tlatelolco? The great pyramid of Tlatelolco is located only 1.9 Km from the Templo Mayor of Tenochtitlán. That means, Tlatelolco divides the line connecting the pyramid of Tenayuca to that of Tenochtitlán in two segments of 1.9 and 9.4 Km; the total segment length being 11.3 Km. This means that the distance Tenochtitlán-Tlatelolco is exactly 1:5 of the distance Tlatelolco-Tenayuca.
And there is more. This first alignment Tenayuca-Tlatelolco-Tenochtitlán-Cerro de la Estrella appears to be at a right angle with another equally impressive alignment, also crossing through the Templo Mayor of México-Tenochtitlán.
The alignment Texcoco-Tenochtitlan-Chapultepec
This second alignment connects the ancient city of Texcoco to the sacred hill of Chapultepec, and in doing so crosses the axis Tenayuca-Cerro de la Estrella at a right angle exactly in its center, that is on the spot occupied by the Templo Mayor of México Tenochtitlán.
The Cerro de Chapultepec, whose summit is now occupied by the castle built for Emperor Maximilian I of Mexico in the XIX century, was considered sacred by the Aztecs. There the Aztec emperors had their baths and gardens, and a temple likely existed on the summit. Several astronomical and geodetic markers are still to be found on the high cliffs below the castle, including some fine bas-reliefs of Moctezuma II and a giant rock sculpture of a snake.
On the opposite end of the alignment, Texcoco was one of the cities of the Aztec triple alliance, together with México Tenochtitlan and Tlacopán (Tacuba). A city of the Acolhuas, Texcoco became one of the most important cities in ancient Mexico during the reign of Netzahualcoyotl, extending itself over 450 hectares on the shores of Lake Texcoco. The city became a major center of learning, and has been often described as the “Athens” of ancient America; home of poets, philosophers and astronomers, as well as to one of the largest libraries of the pre-Columbian world. The great temple of Texcoco was apparently second only to the one of México-Tenochtitlan, and the legendary palace of Netzahualcoyotl, consisting of some 300 rooms and all built of dressed stone, was still a wonder to behold at the time of Bullock’s visit in 1824. 
|An ancient depiction of the Templo Mayor of Texcoco, with its twin sanctuaries at the top, from the Codex Ixtlilxochitl , early 16th Century [Codex Ixtlilxochitl, fol. 112V]|
Very little remains nowadays of the former glory of Texcoco. The last remnants of the great temple of Texcoco were demolished sometime around 1880 to make material for construction, but its location is accurately marked in XIX century maps at a place known as “Cerro de La Simona”, along the present day Calle Guerrero, and between the Calles Allende and Aldama. This position allows drawing a precise alignment between the Templo Mayor of Texcoco and the Templo Mayor of México-Tenochtitlan, pointing to the sacred hill of Chapultepec (itself a major natural landmark on the immediate shores of what was then the lake of Texcoco).
The alignment Texcoco-Cerro de la Estrella-Cerro del Ajusco
Something very interesting also happens when observing the alignment between Texcoco and the Cerro de la Estrella. A prolongation of this line points straight to the summit of the Ajusco; the highest peak, with its 3,930 meters, within modern Mexico City boundaries and one of the most easily recognizable landmarks in the entire valley of Mexico (its highest point, called Pico del Aguila or Eagle’s peak was considered sacred since ancient times, and does indeed resemble a giant spread eagle from the distance).
The triangle Texcoco-Teotihuacan-Mount Tlaloc
Texcoco is also at the vertex of an isosceles triangle, that if forms with the ancient sacred sites of Teotihuacan and Mount Tlaloc. The distance between Texcoco and Teotihuacan and between Texcoco and the summit of Mount Tlaloc is the same and equals 12.5 Km. This is suggestive of a system of survey points or triangulation markers.
Teotihuacan was one of the major ceremonial centers of the classic period in the valley of Mexico, a city whose influence extended as far as Guatemala and the Maya region. On the other hand, Mount Tlaloc, with its 4,151 meters, is one of the highest points in the valley of Mexico, and a sacred mountain connected with the cult of the rain-god Tlaloc. The pre-Hispanic sanctuary on its summit is believed to be the highest archaeological site in the world, and consists of an imposing platform approached by a stone causeway, from whose summit the view easily embraces the entire valley of Mexico and beyond.
Connecting the dots
After connecting all the dots, the resulting figure resembles an enormous kite, having at its four vertices the sacred sites of Texcoco, Tenayuca, Cerro de la Estrella and Chapultepec. The observation points of Cerro del Ajusco, Monte Tlaloc and Teotihuacan remain outside of this figure, but are placed symmetrically with respect to each other and to the overall figure on the ground. The Templo Mayor of México-Tenochtitlan occupies the center of this scheme, at the intersection of the two major alignments.
It is interesting to note that while the location of the great temples of Texcoco, Tenayuca, Tenochtitlan and Tlatelolco, as well as of the sacred city of Teotihuacan, reflects a deliberate artificial construction, the natural landmarks of Chapultepec, Cerro de la Estrella, Mount Tlaloc and Cerro del Ajusco are prominent landscape features over which human design could have had no role.
It was probably from the observation that the remarkable hill of Cerro de la Estrella lies virtually at the center of the triangle formed by three other major natural landmarks: the Cerro de Chapultepec, Cerro del Ajusco and Monte Tlaloc, that the position of all the other sites could be determined.
The prominent role of Teotihuacan in this system of alignments suggests that at least part of this design might date back to the time in which the great city exerted its dominion over all of Central Mexico (that is, at least in the 2nd Century BC), a time therefore much earlier than that of the Aztecs.
The location of the great temple and the city of Texcoco was likely defined relative to that of Teotihuacan (which already existed at the time), of Mount Tlaloc, Cerro de la Estrella, Cerro del Ajusco and Chapultepec. This location is almost “miraculous” in that it is exactly equidistant between Teotihuacan and Mount Tlaloc, and is also found on the prolongation of the natural alignment between the Cerro del Ajusco and Cerro de la Estrella.
The position of the Templo Mayor of México-Tenochtitlan was subsequently defined along the line of sight between Texcoco and Chapultepec, in such a way that it would perpendicularly intersect a line drawn through the Cerro de la Estrella and to Tenayuca.
The location of Tlatelolco is even more interesting, in that it is situated along the axis Cerro de la Estrella – Tenochtitlan – Tenayuca, and also marks the point in which a line of sight drawn from Teotihuacan to the Cerro de Chapultepec intersects this latter axis.
This systems suggests a very advanced (for the time) knowledge of cartography and trigonometry for the purpose of triangulation, and also highlights the existence of a network of alignments of sacred sites based on ancient lines of sight, which has surprisingly gone virtually unnoticed for the past 500 years. It also suggests that the location chosen for some of the major temples and ancient cities in the valley of Mexico, including the very Aztec capital of México-Tenochtitlan, is not arbitrary, but rather the product of an elaborate geodetic scheme that incorporates pre-existing natural as well as artificial landmarks.
 The Board of Longitude, established in 1714, rewarded John Harrison for the invention of the marine chronometer in 1773. Before that, longitude could only be crudely determined with the so called “Lunar distance method”, first devised by Galileo Galilei in 1612, who noticed that the relative positions of the Moon and Jupiter could be used as a sort of universal clock; a method which however required accurate knowledge of their orbits and cycles.
 The chief archaeologist and director of excavations at Tlatelolco, Salvador Guilliem, even goes to the point of suggesting that these three pyramids, those of Tlatelolco, Tenayuca and Tenochtitlán, bear such close similarities to each other that can only be explained if they were erected by the same builders.
Descubren en Tlatelolco Pirámide más antigua que Tenochtitlán, in La Jornada, 27/12/2007, accessed on-line: http://www.jornada.unam.mx/2007/12/27/index.php?section=cultura&article=a04n1cul
 Enrique Juan Palacios, La Orientación de la Pirámide de Tenayuca y el principio del año y siglo indígenas, Contribución al XXV Congreso de Americanistas de la Plata, Buenos Aires, 1932. Accessed on-line: http://www.revistadelauniversidad.unam.mx/ojs_rum/files/journals/1/articles/4006/public/4006-9404-1-PB.pdf
 Massive Ancient Pyramid Discovered in Mexico, The Guardian, 4th May, 2005. Accessed on-line: http://www.nbcnews.com/id/12173346/ns/technology_and_science-science/t/massive-ancient-pyramid-discovered-mexico/#.VaWZ2qRViko
 William Bullock, Six Months Residence and Travels in Mexico, London, 1824, p. 383-395