Teotihuacan

Teotihuacan was an ancient city located in central Mexico which was prominent from 150-650 AD (Murakami, 2018). At its peak, the city covered 20 square kilometers (8 square miles) and had a population of 150,000 people (Barca, 2013). The city boasts several pyramids, large architectural structures, and art that influenced Mesoamerican life (Cartwright, 2015).

HISTORY

Beginning around 150 AD, an accumulation of different Mesoamerican ethnic groups congregated to the area. They created an irrigation system supplied by spring water and began constructing large scale structures (Cartwright, 2015). Compounds and neighborhoods were formed based on ethnic origins (Barca, 2013).

They possessed valuable obsidian deposits and also traded cotton, salt, cacao, feathers, and shells. Corn, beans, squash, tomato, avocado, prickly pear cactus, and chili peppers were farmed on their fertile soil. They hunted rabbit and deer, while dogs and turkey were raised for food. Crafts and textiles were also created and exchanged (Cartwright, 2015).

The Teotihuacan religion worshiped several gods that were often displayed in their art and structures. The Spider Goddess is thought to be the most important to Teotihuacans. Other gods that were praised were Chalchiuhtlicue (the Water Goddess), Tlaloc (the rain and war god), the Old Fire God (the creator god), and Quetzalcoatl (known for agriculture renewal) (Cartwright, 2015).

Their large military conquered surrounding territory and expanded the Teotihuacan presence throughout Mexico. By 600 AD, many structures and works of art were destroyed, marking the downfall of Teotihuacan. The source of destruction is still unclear but theories suggest either an external overthrow or an internal struggle due to scarcity of resources (Cartwright, 2015).

City Layout

A unique aspect of the city itself is the geometrical planning of the buildings and complexes. The layout can be described as symmetric and proportional, indicating that a master plan was used along with a standard unit of measure (Oleschko, 2002).

The structures are aligned with two perpendicular axes. These axes intersect at the Ciudadela and the Great Compound, dividing the city into four. Most structures have an east-west orientation. Researchers believe this orientation was guided by the stars (Oleschko, 2002).

The Teotihuacan Measurement Unit

Many researchers have proposed what the Teotihuacan standard unit of measure was, but have not reached consensus. The discrepancy could be due to some structures being planned and measured with the standard unit while others were not (Oleschko, 2002).

Although researches cannot agree on what the standard unit of measure is, they do agree on its existence. They refer to it as the TMU, the Teotihuacan measurement unit. It is believed to be connected to the relationship between space and time (Oleschko, 2002).

Some researches applied fractal analysis techniques to determine the TMU. A radar image and aerial photographs of major structures were used for analysis. In this technique, fractals (shapes with irregular and fragmented patterns) which are considered isotropic (same properties in all dimensions) are used to estimate the fractal dimension of the image. From the findings of the fractal analysis, the most probable proportional multiples used in planning were eight and three (Oleschko, 2002).

To connect space and time, a hypothesis was proposed that Teotihuacan’s adopted the 365 day solar calendar and the 260 day ritual calendar. The two calendars have only one common divider, the number 5. By dividing the calendar days by 5, the numbers 73 and 52 are obtained. Both of these numbers are known to be significant. It takes 52 years (of 365 days) to return to the same New Year’s date in the 260 day ritual calendar. The number 73 is known as Tonalpohualli’s number in a cycle of 52 years (Oleschko, 2002).

From here, it is assumed that the height of the Pyramid of the Sun was 73 TMU and the height of the Pyramid of the Moon was 52 TMU. By dividing the known heights of the pyramids by these numbers, 0.8630 and 0.8077 are obtained. Since the actual pyramid heights are only estimates, this could explain the difference in TMU values. The height of the Quetzalcoatl Pyramid has the least uncertainty in its measurement and is proportional to 0.83 meters. From these findings, it is proposed that one TMU is equivalent to 0.83 meters (Oleschko, 2002).