Wednesday, October 12, 2016

What Lies Beneath: the Urban Excavation of Tenochtitlán

         The relentless summer heat is finally abating and pumpkins have surreptitiously started making their appearances around town. An entire cemetery seems to have sprouted overnight on my neighbor's front lawn. In the spirit of Halloween, my thoughts, along with half of Birmingham's, have turned towards the beloved horror flicks of my youth. In particular, I've been thinking about the classic (and somewhat offensive) movie trope: Indian Burial Ground. If you grew up watching Pet Sematary, The Shining, or pretty much any other scary movie from the 1980s, then you probably decided at an early age that checking for an Indian Burial Ground under the foundation should be an integral part of any home inspection. While we may have moved on in recent decades, both in movie premises and in terminology (I'm thrilled the ambiguous misnomer, “Indian,”is finally leaving the vernacular), the fear of what lies beneath may have only solidified, particularly if you live in Mexico City.

          Those of us in the United States are no strangers to the controversy involved with developing sites that are already home to precious archaeological resources. However, for most of us, the frequency of coming across these issues just isn't enough to become a practical concern when planning a renovation or construction project. On the other hand, if you own property in Mexico City's Centro Histórico, you might think twice before calling that contractor over to take a look at the cracks forming in your basement. The magnitude of buried archaeological remains is incomparable to any urban center in the United States, possibly in the world. They're taking it seriously, too. Before any major work can be approved, you're legally obligated to allow archaeologists to inspect the site. If any remains are found, it's up to you, the property owner, to fund the excavation.

Zócalo, a pedestrian square in the Centro Histórico of Mexico City
         Furthermore, cracks and buckling aren't uncommon sights. Dozens of feet beneath the surface of Mexico City lies the remains of Tenochtitlán, a magnificent metropolis and the center of the Aztec universe. Tenochtitlán was originally built on an island in Lake Texcoco, complete with an intricate system of canals and causeways. Tenochtitlán's Templo Mayor, a pyramid which towered over the city at 197', now rests its remains under the Zócalo, a bustling pedestrian square and one of the most recognizable places in Mexico City. Over time, the massive pyramid and its surrounding structures sank into the area's soft clay subsoil. The lake was filled in, the remainder of the pyramid dismantled, and the Spanish conquistadors built their new capital directly over the old one (a politic decision, rather than a pragmatic one). Today, at the Zócalo, sits the The Metropolitan Cathedral, a beautiful Spanish-colonial building which took over two centuries to construct and is a historic gem in its own right. However, the presence of the Sacred Precinct directly underneath presents more than just an archaeological conundrum. As water is pumped from wells running beneath the city, the clay contracts, but the density of the buried stone structures remains constant. Consequently, streets buckle and curl atop them. Foundations are compromised. The largest cathedral in the Americas is at peril, not to mention countless other structures. As Eduardo Matos Moctezuma, the lead archaeologist of the project and a local hero, poetically put it, “It’s the vengeance of the gods. The cathedral is falling and the monuments to the ancient gods are what’s causing it to fall.”

Artist's rendering of the Templo Mayor
“It’s the vengeance of the gods. The cathedral is falling and the monuments to the ancient gods are what’s causing it to fall.”  

         Under the direction of Matos, serious excavation of the area began in 1978. Despite decades of excavation and 45 Aztec buildings discovered, there's still a long way to go. Sometimes, optimal sites are identified on a small scale, like in the basement of a tattoo parlor. Other times, events, like the earthquake of 1985 or the expansion of the subway system, unearth expansive areas all at once. Only last year, the huey tzompantli (the "Great Skull Rack," mentioned in the Codex Duran) was discovered during a dig beneath a building on Guatemala Street. While typical excavation sites elsewhere are identified by GPS coordinates, Tenochtitlán's digs get street addresses. Even though it slows the process, maintaining the structural integrity of the buildings above has to be a priority. Often, archaeologists find themselves in narrow shafts, dozens of feet beneath the surface, suspended on their stomachs (I believe this scenario was featured in my last nightmare). Despite the challenges, the work will continue.
Excavating the huey tzompantli
Would you like to find this in your basement?

         Whether grand or humble, famous or ordinary, each building you pass in the Centro Histórico hides a secret beneath its foundation.

“That whole part of the city is like a graveyard of people and of significant cultural objects,” David Carrasco said. “And they awaken every time Mexico reaches for its future.”

         In conclusion, I'd like to take a moment to acknowledge the wisdom of our younger selves; and, as if you needed another reason, I hope the structural and regulatory complications have persuaded you to never, ever build your home on top of Indian Burial Grounds...

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