Construction

In order to construct the massive pyramids and structures characteristic of Teotihuacan, building materials needed to be sourced, curated, and brought to the city. Materials were chosen for various applications based on their properties and availability.

Materials

Many building materials were obtained locally in the Teotihuacan Valley, including extrusive igneous rocks, volcanic tuff, mud and wood. Some materials were obtained from non-local sources such as lime and some andesitic rocks (Murakami, 2015).

Basalt and andesitic rocks were largely used for fill and masonry. Tezontle (scoriaceous basalt) was the most used material due to its properties of being porous, light, and workable. Along the mountains of the valley, basalt boulders were extruded and made into slabs easily due to their stratification. Non-local andesitic rocks were brought in to create stone blocks. Volcanic tuff was used as a base underneath flooring. Basaltic breccia (a combination of pyroclastic rock, basalt, and clay) was used for surfacing building components such as walls, floors, roofs, and stairs. Mud was used for fill, bricks, clay amalgam, and cementing material. Lime was used to make plaster which was applied to clay amalgam and stone blocks. Wood (usually pine) was used to construct roofs, posts, and lintels (Murakami, 2015).

Andesitic Rock

Square and rectangular shaped rocks were a common building material for buildings, pyramids, residential structures. Two types of extrusive igneous rocks were highly used – andesitic rock and tezontle (basalt). Tezontle was favorable due to being lightweight, having an optimal porosity, and being locally sourced. Andesitic rocks were harder to procure and had to be brought in from surrounding areas. The organization of cutting and transporting these rocks provides insight on the social structure of Teotihuacan (Murakami, 2018).

Around 200 AD, major construction occurred in Teotihuacan, resulting in the creation of the Moon Pyramid, Sun Pyramid, and Feathered Serpent Pyramid. Fifty years later, thousands of apartment complexes were constructed. These major pyramids, along with the more “higher class” apartments were constructed with cut stone as opposed to more common building materials such as clay. The cut stone was both durable and aesthetically pleasing making them an optimal choice for these large, eye-catching structures. Furthermore, cut stone blocks did not deteriorate over time, resulting in lower maintenance than other building materials. Lastly, cut stone was used in some sculptures, again due to aesthetic reasons and their structural integrity (Murakami, 2018).

Extracting andesitic rock is a complex process. The location of extraction is chosen based on the desired size of the rocks and the fracture lines of the rock. Using a wedge and a hammer, the rocks can be broken along these lines. This is a very labor intensive process. Since the rocks had to be cut into squares and rectangles along these existing fracture lines, specialized knowledge was employed to pick and cut these rocks (Murakami, 2018).

A study conducted by researchers at Tulane University found that most of the sources for these andesitic rocks were located nearly 10-15km away from the city. This particular researcher suggests that due to the distance of the source along with the specialized knowledge required to extract these rocks, the operation was organized by the state to construct these magnificent structures. This finding provides insight to the social structure of Teotihuacan, along with their construction methods (Murakami, 2018).

Glass shards in Lime Plasters

Plasters were commonly used to cover surfaces of different types of structures in Teotihuacan. These plasters consist of two components: glass shards and lime. Researchers from the University of Calabria and UNAM took samples to determine where these glass shards came from and what they were composed of. The average ratio of binder to aggregate was 0.333 for the sample studied. It is likely that these shards were obtained from the Altotonga magmatic system from an in situ deposit. This system is located 180 km east of the city and would be travelled to on foot (Barca, 2013).

Construction

The first step for constructing the pyramids and other large structures was to lay fill. Construction cells were often used for this purpose. The cells were constructed with wood posts or adobe and tepetate blocks and filled with earth, crushed tepetate, and rocks. Retaining walls were also created to support facades (Murakami, 2015).

Facing consisted of either talud, a sloping wall made from basalt or andesite, or talud-tablero, a sloping wall with a vertical panel usually made from tezontle. These were constructed with rocks bonded with mud (Murakami, 2015).

Walls were commonly made from tezontle and staircases were made from either tezontle and basalt or andesitic blocks. Clay amalgam and lime plaster were applied to walls by making a paste and throwing it at a wall with a trowel until it stuck. For the floors, it was dumped onto the floor and leveled. Typical floors had three layers from bottom to top: crushed tepetate, clay amalgam, and lime plaster (Murakami, 2015).

Timing of Construction

Major construction began in Teotihuacan in the Tzacualli Phase (1-150 AD). At this time the population was rapidly growing (30,000 to 60,000) along with the area it covered. In this phase the Sun Pyramid and Building 1 of the Moon Pyramid were constructed. Residential complexes were constructed near the end of the phase in the Ciudadela for prominent residents (Murakami, 2015).

In the Miccaotli Phase (150-250 AD), construction commenced along the Street of the Dead. The Moon Pyramid was expanded (Murakami, 2015).

More construction along the Street of the Dead began in the Tlaminilolpa Phase (250-300 AD). The Ciudadela was expanded and the Feathered Serpent Pyramid was constructed. In addition, several complexes were constructed, including the Quetzalpapalotl Palace Complex, the Xalla Complex, and the Street of the Dead Complex. The Street of the Dead Complex contained temples and buildings possibly used for royal and administrative purposes. The Moon Pyramid was also reconstructed during this phase (Murakami, 2015).

In the Xolalpan Phase (350-450 AD), many structures were rebuilt and the Sun Pyramid was expanded. The Feathered Serpent Pyramid was damaged and looted during this time. After the Xolapan Phase, major construction projects began to decline, aligning with the collapse of the state administration (Murakami, 2015).